A cool project to install NixOS on a Steam Deck, but with specific drivers, working gamescope session (not nested) etc… It’s working really well on mine, except the transition between gaming/desktop modes that could be improved, but so far, it’s a very good experience 
I tried to install a plain linux, but missing some specific patches here and there (mangohud, gamescope, kernel), I also really missed a proper fan control, while working out of the box on recent kernels, they are always at some minimum level that produce noise while idling…
Alternative ChimeraOS is nice too, they chose an interesting way to provide a web interface for installing non-steam games, that’s very nice.
Finally, HoloISO, a SteamOS open source reimplementation, it didn’t work well for me, it was constantly asking me to log in on Steam at every reboot…