A patent that is over one-year old reveals what appears to be a Switch tablet without the controllers, but it can also show a way to play games on more than a single display, similar to the Sifteo Cubes "intelligent game system" which has been discontinued more than three years ago.
https://www.notebookcheck.net/Next-gen-Nintendo-Switch-might-pack-multi-display-features.299250.0.html