Even for portability they have the 8bitdo Lite which is smaller than most modern phones. Wider surface area, fits in a small pocket. Works well with a tablet or laptop gaming setup.

This is good if you want even more portability, for a cheap $25 bluetooth controller with pretty great platform support. Some of my friends go to a lot of conventions and I can see them having a couple of these in a small pocket just to have something easy for multiplayer games.

For me, I’d likely use it like they show in one of their promotional images - keyboard shortcuts in art programs, etc.