Nobody has to have instructions on how to "hack" the Steam Deck because it's a computer and you just run whatever you want on it.

The instructions on how to crack open the immutable OS image are readily available from Valve but you probably won't need them since it's already got a lot of power even without that.

If open _hardware_ is the requirement, rather than just a nicety, how many graphics cards can you actually support?

I mean, I know there are a bare handful that can run Quake I. But I don't think there are that many, that can do more.

SteamOS 3 is Arch Linux-based, and should allow most popular game engines to run fine. =3