I firmly believe there is design space for a psychic/psionic caster in the game and the approach of only doing psionics via subclasses is flawed. Though I myself loved the psion in 3.5 and 4ed so maybe I'm biased. But anyway as the title says. 

There is a UA class called the mystic, it might be what you are going for. They won’t except It in adventurers league.

It likely won't be accepted in many games since WotC has abandoned development on the mystic so thoroughly, they even call it out in the latest UA several years after it was originally abandoned. 

Unfortunately the Mystic was shut down. It didn't make the cut out of playtest. Personally, I think it's unfortunate there isn't an official full class psion yet. I've been a fan of psionics since AD&D but admit it was unbalanced. With 5e having the aim of making D&D simpler (easier) I understand how it's tough to get a full psion class to fit in. I do think it can be done though and I think it's a good time to do it. With so many new players, learning new things, it would be a good time to learn psionics as well.

I absolutely agree that there should be a full psionic class.

Well, let’s try to make a balanced Psychic class, or at least ideas. (I have not played 4e or 3.5).

https://www.dndbeyond.com/forums/dungeons-dragons-discussion/unearthed-arcana/63478-new-psi-based-ua

Just as long as a full Psion is not any kind of “Spellcaster” I’m okay with it. Psionics=/=Spells

I agree, in the Forgotten Realms psionics was unaffected by anti- magic effects, it would be a great class.

An ability similar to mage hand could be cool 

I kind of like how there isn't a psion/mystic class, and instead ANYONE can have those types of power.

Edit:  I think there should be a psionic option for every class.

I don’t mind others having access to Psionics, but I do think that there should be a full blown Psionicist with subclasses and everything. And I don’t mind if psionics are “magic” just as long as the don’t “cast spells.”

You have full caster classes (Sorcerer/Wizard) then a few subclasses (Eldritch Knight/Arcane Trickster) for the other classes that allow them to dabble in magic.

Psionics should be treated the same way.  Make a base class (Mystic/Psion) and then Subclasses (Psi-Knight/Soulknife) for other classes.  

Quote from Golaryn >>

You have full caster classes (Sorcerer/Wizard) then a few subclasses (Eldritch Knight/Arcane Trickster) for the other classes that allow them to dabble in magic.

Psionics should be treated the same way.  Make a base class (Mystic/Psion) and then Subclasses (Psi-Knight/Soulknife) for other classes.  

 Agreed. I would specifically make “1/3 Psion” subclasses for the Monk and Barbarian. 

I think those are all good points and I'd totally be down to help create a full psionic class. However, without knowing all the reasons the Mystic was abandoned coming up with a class that doesn't suffer the same pitfalls would be very difficult.

I do feel like it should start much more limited as a way for new folks (Especially those who didn't play earlier editions where psionics were present) to get their feet wet so to say. I'm not positive but I think one of the reasons the Mystic failed is that it was just too much. Too complex and too much information for a new player to absorb unless you were really really dedicated. I think that stripping down to a bare minimum of what makes a psionic class would be a good place to start and then be extremely careful about feature creep making it too complex.

At first level you could get psi points. You can use these to do stuff like, lift a small object, know someone’s name, or to know if a person has seen someone before recently.

(sorry for errors)

Whatever it is, it will probably have to utilize the Psi Talent die from the UA.

There should definitely be a Psionic Class, full class, without spellcasting as their key ability.

They could have psi points. I don't like the psi dice mechanic, but everyone seems to disagree with me, so it would likely have that as well. 

Quote from LeviRocks >>

There should definitely be a Psionic Class, full class, without spellcasting as their key ability.

They could have psi points. I don't like the psi dice mechanic, but everyone seems to disagree with me, so it would likely have that as well. 

 Wanna make another bet? I’ll bet you a weak of Homebrew scutwork that if you give the PsiDie as it exists a chance for, like, 1 adventure (not a whole campaign, just an adventure), that you will realize it doesn’t suck. Take a character from level 3 to say, level 6, just enough to get a taste of both tiers. If it hasn’t grown on you by the end of it, you can dump a whack-ton of homebrew you don’t feel like making and I will figure it all out to save you the work. 

Quote from LeviRocks >>

There should definitely be a Psionic Class, full class, without spellcasting as their key ability.

They could have psi points. I don't like the psi dice mechanic, but everyone seems to disagree with me, so it would likely have that as well. 

 I don't like the psi dice either. I think it's an unnecessary complication, adding a new mechanic. I think the psi abilities and points could be managed in a way similar to spell slots and ki or sorcery points. Not saying they would be "casting" but having a pool of psi points that could be drawn from with the different level abilities. As they are drawn from they get checked off until their are no points left and you reach a state of mental fatigue. Needing to rest to replenish.