I currently have a load of pirated games and I'm considering moving my systems to Linux cuz Windows is ass. Would this make it difficult to run pirated games?
Yes both launchers can use proton-ge as a wrapper similar to what steam dose.
As for recommendation, pick what you like. Both programs fill the same function and are both FOSS. Heroic has a nicer interface, Lutris has an option to show logs while you are running a game that can help with debugging if the game doesn't work for some reason.