how do you calculate the monk unarmed damage? what level do you count as?

I really like this concept, but some sections are really unclear. For example, I really can't work out how the spell casting is meant to work, the numbers in your examples don't make sense. 

Are you considered to have an ability (for the purposes of qualifying for feats or something) if you have a limited version of it from this feat?

I adore this feat and can see the effort you put into it. you have no idea how long ive been looking for a feat like this to round out character concepts like a wizard barbarian or a fighter rogue but never wanting to multi class (mostly because i dislike multi classing) but this provides a great alternative.

id personally continue to add scaling till about mid tier (level four or five for casters, rogues getting uncanny dodge ect) I also wouldnt put a limit on how many times you can take it as it gives no stat bounces so you are trading a huge boon of a plus one to one stat for these abilities.

for the warlock i think it would be better to mix pact magic and otherworldly patrons and make the third a pact boon, as that in its self is very very strong. if you would like to talk more about it just hit me up ill throw my discord your way

Id also put these into separate feats so you can give each one the T and L it need to be clear and fun

I really like it, but I just look at the proficiency limit on the classes and all i can think is that there are some people that can't possibly use this feat because they would have to take Skilled to even get the proficiency first. 

Hide in Plain SIGHT, I believe

Been a while since I went back to this due to IRL stuff. These are great comments. Soon as I got the free-time I'll work on revisions. I'll start with the spell progression, which definitely needs some major tuning.

There could be a bit more clarification on what abilities are unlocked through the Archetypes in the prime column. For example, stating "if selecting Roguish or Martial Archetypes, gain its level 3 abilities, for Arcane Tradition, gain its level 2 abilities" and so on. This would also help with specific subclasses like the Rogue's inquisitive, which has three level 3 abilities, one of which would be lost with current wording (unless that is the intent). This could also reduce confusion for some who may not understand what "first two" explicitly means. 

How is the pool for Lay on Hands calculated?  If it's based on character level, that is incredibly overpowered.  If it's as if you have a single level in paladin, it's just bad.

I would like to know how the scaling of Rage/Martial Arts/Lay on Hands/Sneak Attack work.
Are they 1 single level at all times? The character level? Half of it (Like the Warlock invocations)?

Also, you can really use Divine Smite without spell slots, so do you get them from the feat or would you have to get them from another class? 

This is ridiculously OP. I am only so far looking at Spell Initiate, but if you want this much of another class, you should be multiclassing.  Even gaining one level of spell casting as you described (2 cantrips, two level 1 spells slots, 2-6 spells known), overshadows magic initiate, the closest RAW feat we could compare this to.

Your framework as is, would mean in a mere 2 more levels after gaining this feat (so as early as character level 6 if we put aside fighters and vhuman), depending on the caster you chose, would result in  2 - 4 cantrips known, four level 1 slots, two 2nd level slots, and 5 to 10 known spells. I am going to assume ritual casting is is excluded, nor can a wizard scribe new spells into their book.

Let's compare this to Magic Initiate; you get 2 cantrips, and one first level spell, that you can cast once per day. It is also NOT a spell slot, so can't directly interact nearly as well as with any spell casting class you may have.

Honestly, I do not think your frame work of progression without any further investment or cost, can remotely be balanced. If you care about balance, you have to throw that out.

The simplest solution if you care about balance, would be to make magic initiate the first step in a feat tree, where any further progressions requires further feat investment. If you don't care about it being strictly balanced against raw, but want to maintain some semblance of balance, I suggest the same, but with a moderate buff to magic initiate to more align with a level 1 caster and your concept. 

You will also need to codify this better, both for simplicity's sake, as well as for clarity and balance between the different caster bases. This should be achieved within the feat, the player shouldn't need to refer to class specific pages (beyond selecting spells). You didn't address how potential prepared casters work at all; if they functioned like the base class, they are clearly the superior choice by a significant margin.

To do all this, firstly, I think they should all effectively be treated as known spell casters (even if a prepared caster is used as the base). The first feat investment should correspond slightly below the average (sorta) of 1st level casters.

• Cantrips Known: 1
• Level 1 spell slots: 2 (regained on a long rest)
• Four spells known.

No progression period until they invest in another feat. This does move beyond both the power and versatility of Magic Initiate, but not the extreme measure your framework does. Do not underestimate just how useful it is that you are gaining spell slots here. NO other feat does this, the slots on their own are arguably worth the feat investment.

As for the 2nd feat, even if investing in a two, getting the core class abilities is kinda bullshit to be honest, and if nothing else, will result in a even more obviously better half caster, then an actual half caster. I do not think a 3rd feat is even necessary.

Below is NOT additive, but the new TOTAL.

• Cantrips Known: 2
• Level 1 spell slots: 4 (regained on a long rest)
• Level 2 spell slots: 2 (regained on a long rest)
• Seven spells known.

I think they should simply scale up slightly in spell casting progression, but they should fall below gaining 3rd level spells. That is a serious time investment for a half caster, taking until level 9 to achieve, and even with 2 feats, you  should not be superior to a single classed half caster.

I also think you should lower the ability requirement for the first feat to 13, so it aligns with others, but the 2nd feat should increase to 15. This means if they truly want to invest in this just like is often required of a true half caster, if you really want to focus more towards your spells, you need to sacrifice something elsewhere, and a 14 really doesn't do this. 

A fighter (non-eldritch knight) with their extra stat bumps, would in fact keep pace with the Half-Casters at this level, plus have cantrips (and the same amount as an artificer at this level), plus maintain their fighter progression, and if they really wanted to push this concept further, they can stack all this with eldritch knight.

The rogue would fall slightly behind, but again, they could stack this with the Arcane Trickster also.

If you insist on gaining some of the core classes ability, I think this, and this alone, is what the 3rd feat should be. That requires serious investment, and might excuse stepping on the core classes toes. It still should even then be a lesser version compared to the core class, but here is where you could justify some character level scaling to occur. I suggest looking at Martial Adept as inspiration, if it had a modest buff or amount of scaling.

Because of this, and again simply for the sake of clarity, each of these should be broken down and included directly within the feat, as much as possible the player should not need to look it up elsewhere.

My final suggestion directly follows from the last, I think you really need to break each base class into separate feats along with the 1st, 2nd and 3rd feats in the trees also being separated again.

Sneak attack is nice, but cunning action is better. Plus what if a human takes the feat at lvl 1 they could choose to get action surge early.

I don't know if this is due to revision, but the Spell Initiate and Spell Adept explanation is quite unclear. For example:

For example: If a Fighter takes Spell Initiate for Bard for her factotum feat at character level 4, she will [...]. If she hits character level 3...

Hasn't the fighter already hit character level 3?

I really like the concept here of a sort of different kind of multiclassing. I suggest breaking up this feat into different ones for each of the class features, probably after the fine tuning you do with the other suggestions. That way you have the room to write out all the feature descriptions individually. 

Should this feat be visable anywhere? I cant find a way to choose class from this feat

These seems like a nice way to make Gestalt characters.  If not then its very strong and OP.  A variant human is gonna get this at first level which will make the character almost second level at creation.  This seems to be a way to multiclass without the punishment of losing a level in the main class.

That being said, I do like the idea of feats that can give you class features from other classes so long as its not too overpowered.  A feat to gain sneak attack might be nice.

I love the concept, but I'm not sure quite how to implement it on D&D Beyond.

This is absolutely massively overpowered for a feat, even with the lack of clarity of certain abilities (like sneak attack, how many dice does the character get?). The game is balanced around these core class features belonging to different classes - it's what sets them apart. Giving the most important core features (unfettered) to a character without the need for multi-classing breaks that very central premise of balance. I would never allow something like this at my table. It abuses the feat system by allowing them to be applies as a loophole around a specifically designed balance element (multi-classing).  If you read through the early UA documents, they explain concepts in the game design which this 'feat' completely breaks. This is the same reason that eldritch adept does not allow any prerequisite invocations (thus denying the signature eldritch blast invocations to non-warlocks). ASIs should not be treated as equal in gravity as a full level in another class. Your 'feat' does exactly that - it removes the need for a character to make the difficult choice  of sacrificing a level in their primary class to get core class features of another class through multi-classing.

I would suggest making the requirement for Fighter to be either STR or DEX