Some considerations:
* Games that are strictly turn-based can be played one-handed. This includes (traditional) roguelikes (Tangledeep, for example, should be playable one-handed), as well as games like the Wizardry series (not counting 8, though even that's probably doable one-handed) and Might & Magic 1-5. (Ultima series is trickier here; I think 4-6 are doable. Maybe 3, though it makes you skip your turn if you take more than 5 seconds to make a move. 1 and 2 I'm not sure about it (though, 2's main real-time element, landing a space vehicle, can be easily done one-handed).
* Turn-based strategy, for example, should be playable one-handed, unless the developers did something that doesn't fit that genre. This includes SRPGs like Fell Seal: Arbiter's Mark.
* Some games allow remapping controls. For many of those games, you might see if you could remap the controls so they're all reachable with one hand.
* I know for a fact that VVVVVV supports one-handed play even without control re-mapping (don't remember if it's been added yet). There's only 3 controls needed in real-time here: left, right, and flip. Furthermore, there's multiple choices for each one. (Other controls are for things like pausing, looking at the map, reading messages from terminals, but not anything you actually need to do while dodging things or timing flips.)
SultanOfSuave: Not everyone is going to have the misfortunate of lacking their dominant hand, and not everyone wishes to play on the hardest difficulty setting.
Mafwek: I think RTS games are in the same group as FPS games and other action games that they have to be played with both hands, and modern RTS games have better AI than old ones had.
If I am making a list after my hand heals, I am putting RTS games only in theoretically playable.
Sometimes a game that's "theoretically" possible might be doable if you play on an easy difficulty and/or slow the game down (if there's an option to do so).
Speaking of slowing the game down, it occurred to me that Celeste (not on GOG, but DRM-free elsewhere) might be doable, thanks to there being an assist mode that allows that sort of thing. On the other hand, that game doesn't need that many controls, and could be done one-handed; just bind jump and dash to keys near where your hand sits for moving. Actually, you could even do this on a standard gamepad; use the left d-pad/analog stick for movement, but bind jump and dash to the left shoulder buttons (sometimes called triggers).
(For those disabled long-term, there exist one-handed controllers, and it may be possible to play more games like that. But since your situation should only last a few weeks, that may not be worth it, unless you're able to somehow borrow one.)
Edit: One other issue with Celeste is grabbing walls (which I forgot about). I think there may be some option to help you there, like being able to turn grab into a toggle.
Speaking of which, any option that allows you to turn something into a toggle rather than having to hold a button/key is useful here.
It occurred to me that Dead Cells might be doable, at least on some level, with assist mode and key remapping. There's an assist mode that will make you auto-attack with the melee weapon you're carrying when there's an enemy there, for example.
And then Crystal Project got an auto-jump option that should make the platforming parts doable one-handed. (The RPG aspect of the game is turn-based, so no issues there.)
