Valve's popular handheld gaming PC recently passed 14,200 officially rated games, meaning there's never been a better time to own one.
This is just talking about games approved through Valve's verification process. There are a lot of games that work that are "unverified", not to mention the entire history of gaming available through emulation.
@Fubarberry My one wish is they (Valve, Nintendo, etc.) could make discovery easier and more useful. It takes a lot of effort finding new games to play that aren't the usual major releases and obvious indie titles.
I'll check those out. I've been doing the "steam discovery queue" for awhile now though, and it feels like if you do it enough you won't ever miss anything of interest. I think it can work pretty well for game discovery, you just need to invest some time in it every day to get through all the more "common" recommendations.
Steam has a built in discovery queue that contains a list of games it thinks you might like (and it it infinite, so it technically contains every game on the platform)