Basically yes, in a way.
There are devices (I think Roland made something like) that is a freestanding box which plays a midi file, from disk, or maybe card or similar. This must have some sort of OS that does little else.
Also some of the keyboards are sophisticated enough, incl disk drive etc, that they might tick your box.
But such devices are essentially parasitic, they are little use on their own. They assume you have a general computer (system) available to create the original material, or do all the other needed tasks. The keyboards (WorkStation) maybe less so, but still totally within the restrictions of the facilities of the specific device.
Could be a useful thought, you'd sure get rid of all the problems re latency etc if the system got rid of WinDoze, and just got on the the important (midi) things.