A small set-top box (essentially a Steam Deck with the screen, controls and batteries removed, and with components that don't have the space restrictions that come with a mobile device) would still be an interesting proposition. Particularly if they partnered with the main video streaming services to port their apps across, and implemented Chromecast/AirPlay support.

I can see a market for it, as a "Chromecast and Apple TV competitor that also plays all your games".