Those are the only officially supported devices. They do also provide instructions on how to install SteamOS on other devices, and even encourage feedback on the experience.
They provide the instructions, but last time I checked they took down the install files. Im hoping they come back because i would love to give it a try on my system.
Edit: Just rechecked and it looks like everything is there including files. I know what im doing tonight!
They do not list support for desktops, only Steam Deck and some other handheld devices.
Those are the only officially supported devices. They do also provide instructions on how to install SteamOS on other devices, and even encourage feedback on the experience.
They provide the instructions, but last time I checked they took down the install files. Im hoping they come back because i would love to give it a try on my system.
Edit: Just rechecked and it looks like everything is there including files. I know what im doing tonight!