Steam Deck hits over 4,000 titles marked either Verified or Playable
www.gamingonlinux.com
As more developers work to optimize their games for the Steam Deck, a bunch of Native Linux games release and Valve continue improving Proton - the Steam Deck continues to see more games go through Deck Verified and there's now over 4,000 listed officially.

And many more work out of the box, just not officially verified.

At this point it’s probably safe to assume that all games work with Linux, unless some crazy anti cheat or DRM explicitly bans Linux users.