Honestly, we're so far that it's easier to look for unsupported games. Those include those with draconian anti cheat (see https://areweanticheatyet.com/) and those that can only be installed with the Windows store like Minecraft Bedrock edition (but for that the Android version works) and Gamepass games.
Even if a game doesn't look like it'll work based on protondb, try it anyway. Many times I've had games that were marked as low ratings start up without any changes lol. I remember even when d4 beta came out, I saw people struggling to install and play it on the first weekend... Worked out of the box for me.