Most of my games work right out of the box, and the ones that have problems are ones that I'd also have to fiddle with for more than a 1-minute check to ProtonDB are ones I'd have to fiddle with on Windows. However I also do not touch anything with online multiplayer or anticheat, and I know games with kernel-level anticheat tend to not handle Linux well on anything but a Steam Deck.

I swapped a PC I had mostly for gaming over to Linux. I'm having a pretty nice time.

As for piracy, I know pirated games that need to be emulated because they are originally Nintendo Switch games or something work well. No idea for pirated PC games.