Nano or mini FC for PX4

Hi - I searched the forum but don’t see this question. New custom design+build tiny copter for potential commercial development. The FC size is therfore a critical design element. Smaller is definitely better. Does anyone know of a 16x16 or 20x20 FC board that is PX4 friendly? Sometimes the suggestion of “mini” in the name isn’t indicative of the size (I’m looking at you CUAV V5 Nano). Thanks for any name dropping to point me in the right direction.