If you bought it on Steam, you get it in every “version” (for each OS) that the game was released on. If there’s a Linux runtime, then you’d have both the Windows version, and the Linux version.

Most games don’t have a Linux runtime, and that’s fine. All you need to do is go to “compatibility” in the game settings in Steam, and check the box. Then click the drop-down and select a Proton version (best bet for you is prob “experimental”), and most of the time that’s all you need to do. Protondb.com will tell you if there’s any tweaking needed, or if a specific version of Proton is called for.

This is exactly how the Steam Deck works. Try a gaming-centric distro like Bazzite if you want an even more seamless experience (based on immutable Fedora Silverblue with a bunch of tools and presets focused on gaming. Great for everyday, non-gaming use as well).

Proton is actually incredible. I’ve found that I’ve often gotten better results with running the Windows version of a game with Proton than the actual Linux runtime.