Proton is basically magic. I’ve got 1960 games on steam and I have a chunk that are listed as ‘untested’ but less than 10 that are listed as incompatible. The games listed as untested also usually end up just working. You may have to mess with proton or winetricks sporadically, but even that is very rare in my experience. It is nearly always an issue in a multiplayer game with anti-cheat when it just doesn’t work.
The theory is that you could stretch it to fall under incitement, not sure if something quite like it has ever been prosecuted, but near everyone includes similar disclaimers if they want to do something like this.