I’ve gamed on Linux for the past 5 years. If you use Steam, most stuff works out of the box after you enable a single setting. Now that the linux gaming community is growing it’s easier to find workarounds for the games that don’t work. The only games that are hopelessly broken right now are games with intrusive anti-cheats that don’t support Linux. You can head over to protondb.com and check compatibility status for your games, including workarounds when necessary.
If you don’t use Steam, then I’m not sure. Last time I played non-Steam games there was more troubleshooting and tweaking required but it’s been a couple of years and I don’t know the current state. It’s worth noting that Valve’s compatibility layer, Proton, is open-source and based on other open-source projects. There’s work currently being done to port the functionality outside of Steam. Hopefully, this will mean that in the future all launchers will behave similarly.
But that’s just the software side of things. Don’t forget to check how your hardware works on Linux as well.
How would an NFT help in any way? We’re not lacking the means to prove you bought the game. We’re lacking companies willing to sell you games and laws that prevent companies from saying “buy” when they mean “rent”. If we got to a place where torrenting software you’ve bought in the past is legal, we don’t need NFTs to accomplish it…