The Steam Machine and Steam Frame are probably delayed, but they still intend to release them in the first half of this year.
They said they planned to have a concrete launch window and pricing by now, but hardware pricing/shortages have made that hard to pin down.
They probably said it like that because you can add any executable to steam as a non-steam game and activate the overlay. apparently some programs don’t work? that’s news to me.
Well any game or launcher or emulator have to support the controller or type of controller. In example Valve cannot guarantee that all functionality (like the trackpads and motion controls) are supported elsewhere.