Proton?

Valve puming money in the Steamdeck is paying off for everybody gaming on Linux.

It's a double-edged sword though. It means there's no point in developing native Linux games, because it'll run through Proton anyway. Keeping Windows the default gaming platform still, and making Steam the only way to acquire games if you wanna play on Linux. You CAN add non-steam games to Steam, but they're not guaranteed to work. I don't know if you can also run Proton without Steam because I've never needed to try, but that would be a hassle for your average user.