Here's an up to date look at the current state of the most played games on Steam, and how many of they run on Steam Deck and Linux as a whole.

It’s worth noting that the top 100 games do contain a lot of popular multiplayer games, and multiplayer games are less likely to work on Steam Deck/Linux due to anticheat issues. So games outside of the top 100 will generally have a higher compatibility rate. For comparison, only about 5% of the top 1000 games are broken on Linux according to Protondb