The Steam Deck is powered by SteamOS, a custom Linux-based operating system developed specifically for running Steam and its games. It’s possible to install Windows on your Steam Deck if you wish, but the drivers are rudimentary and there are a bunch of obstacles when it comes to controlling Windows via Steam Deck’s controls or its touchscreen.
A leaked project from an internal Microsoft hackathon shows that staff at the operating system developer have noticed these issues – although it sounds like a version of Windows optimised for gaming handhelds is a long way off.