50/50 that any Nork invasion will stall in the Seoul suburbs she the invaders start coming across things called “supermarkets”. The glorious reunification invasion will quickly devolve into mass looting.
I think you underestimate how brainwashed they are.
There would be no meaningful invasion. Expect a half hour of heavy shelling obliterating most of Seoul, followed by carpet bombing just north of the border and conversion of Pyongyang into a sandbox.