It's really mostly EAC and Co nowadays that are blockers. And this is not because there is no support per se. It has to be allowed though because this stuff does indeed detect that it's not a "real Windows".
Stupid launchers are also trouble sometimes. Looking at you EA!
Anyway, a good source to tell is still the protondb. What's listed there usually works on the Steam Deck too. Or has workarounds explained.