FlightDetent
Our below the wing folks only have to wait for #2 to be shut down before they can start offloading baggage. SOP for APU inop is to taxi in, set brake, either have a gpu plugged in or wait for the jet bridge to saddle up to the plane and connect to that power and then shut down #1.
If we are to “go dark” with an APU but no gnd power we wait until the folks have gotten off and then shut down the APU, etc.
We don’t have a normal procedure to deplane without power and in the 27 years I have been here (there) I don’t recall having that happen. (yet)