Civilian guns (armament generally, not just guns) aren't for going toe to toe with a trained military in the field.

They're for putting a bullet in you and/your your family if you act as a collaborator, taking potshots at the logistics train, and all the other nasty stuff you have to do to make occupation costly in terms of both life and dollars. Every cent spent on putting bullet proof glass in the camera installation van and drone cages on the police station and using those cameras and drones to track down the guy who shot you for collaborating is a cent that must be extracted from either the occupied population or the population that's financing the occupiers and not spent in direct pursuit of the political goal.