You can 
- Install arch linux on your computer with the KDE plasma desktop
- Install steam
Jokes aside: What chromebooks did was to allow Steam (the app) to run on ChromeOS. SteamOS is specifically just for the steam deck, but for practical purposes (running games), just installing the steam app gives you the ~same experience.
Of course you won’t get some of the hardware-specific features such as the FPS locking but you’ll need a steam deck to get that anyways