TFW the game actually works on GNU+Linux
By now I just expect it to work, unless it’s some drm-tastic ultrapopular multiplayer game. I don’t even check protondb any more…
I check PCGW more prominently these days because even if the original game works, you can expect there to be some quirks that exist on Windows as well that Proton accurately replicates.
I always double check for Steam Verified/ProtonDB, but almost every game just works right out of the box for me.
That's wise :)