> Steam you download from steampowered.com can be an open platform at the same time that the Steam that comes preinstalled on the Steam Machine is a closed platform.
i dont think that's possible unless steam choose to go the route of what apple does with iOS and macOS - both essentially are "different" OS's.
But if that's the case, then games would have to be written "twice" (or have engine support directly from engine vendors). I highly doubt this can or will occur, as game developers are short on time as is.
Not my space, but I think this would be a cryptography kind of thing. Burn a key into read-only hardware, lock the bootloader, require the kernel and drivers to be signed with a key the burnt-in key can validate. Potentially extend it to all executables on the device.
It’s closed in the sense that you can’t install whatever you want, not in the sense that Valve is going to make their own framework devs have to use.
Windows has locked down variants. Nobody has to recompile apps to use those.