So I guess this is a broader question than just adding gauntlet as an item in the game. My problem started with Armorer Articficer's Armor Modification class feature. Currently, there isn't a way to target them separately but I've been improvising. Currently, I'm trying to add Enhance weapon infusion on Armorer's thunder gauntlet since it is counted as a simple weapon but DnD Beyond doesn't allow it to do so. I've talked to DM and he allows me to customize my attack to reflect that. So right now I'm trying to find a regular gauntlet that I can use as a placeholder to add the infusion on so they can see it is being used. Does anyone think it's worth it in general just to add common items for gauntlets (we have common items for helmets and boots already)?

Due to the terms of their deal, DND Beyond will only add official things. They won’t add a gauntlet unless there’s an official one made. See the Boomerang. There is no such thing as a normal Boomerang, but they made one to successfully add the Storm Boomerang. This is kind of a weird exception though.

No because they’re already included as part of a suit of armor.  But as a magic item, sure, as a wondrous item, start with gauntlets of ogre power.