What I do in the game to enable 3D is adding another camera so there are two screens in one screen, which is how Google Cardboard works. I was hoping that big 3D glasses would work the same but I really don't know. I don't own such a device...
2d games appear as a floating window.
If it works on GearVR as 3d, it probably works in 3d on Quest, then the next biggest question is does it work with the controllers... That's often an issue.
There are lots of Quest owners on itch.io looking for games now (Sidequest is gaining popularity, but some of the listings on it require visiting itch to purchase the game).