Comment by evilduck

The Steamdeck is a general purpose computing hardware device shipping with SteamOS, it's just an x86 APU with a handheld form factor and SteamOS is just a customized linux distro (but not a proprietary one). Install Windows on it if you'd like, or install SteamOS on any other hardware you'd like (though it's not really meant for this, just go get a more generic linux ISO)