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
Installing windows is lame and ruins the console like experience that helps make deck popular. Also, the anti cheat won’t be solved until Linux anti cheat is used by the games and no sooner. That won’t happen until a lot more people are on Linux.