The difference is Nintendo builds their own killer apps exclusively for the hardware that they choose, so they can guarantee a good experience regardless of the performance level. Steam Deck doesn't have any native games. It's all games written for other platforms first and if the chip's performance doesn't meet a minimum bar then it just won't work.
It's all games written for windows, but at this point valve bankrolls proton and wine development so heavily it might as well be an in-house product. Valve would like all games to be written for Linux (case in point: Steam machines) but the reality is that game devs are slow to adapt and desktop gaming is still largely done on PC.
Nit: it does have the valve on-boarding game for it, but that doesn’t really change your point.
Also Valve do some steamdeck optimizations for every game via their shared shader cache. Which enables it to run a lot smoother than competing portable x86 systems.
> Also Valve do some steamdeck optimizations for every game via their shared shader cache
Isn’t the only purpose of this skipping shader (re)compiling?
As far as I understood it, they did it because compiling shaders both takes long on a handheld device and time is at a premium for handheld players. They don’t want to wait eight minutes for a shader compile.