From the FAQ [0]:
- What OS is Steam Deck running?
SteamOS 3.0, a new version of SteamOS based on Arch Linux.
- Will people be able to install Windows, or other 3rd party content?
Yes. Steam Deck is a PC, and players will be able to install whatever they like, including other OSes.
Arch Linux is amazing. The biggest surprise for me was that it's more stable than so-called stable distros, probably because the various packages don't end up drifting several months from each other when keeping up to date.
Hopefully this eventually results in more user friendly Arch Linux installers. The learning curve is an absolute wall when installing, even after several years on Linux, but after that it's pretty standard.
Based on this trajectory I expect they'll be migrating to NixOS (or maybe Nix on Arch) in about 5-10 years.
Funny you say that! Arch images now ship with an official installer as of a couple of months ago - which is comparable to the Ubuntu or Fedora installers in ease-of-use.