They are likely wired to the 120 volt alternating current system- whether shore power or onan.
the inverter takes DC 12 volt from the batteries ( refreshed by alternator or by 120 volt source) and converts that to 120 AC- most inverters do not have the capacity to run high draw electrical loads- I don;t have your model- some motorhomes only have inverter power on dedicated outlets, separate from the other ac outlets
you may find that on the genny you get to choose between ac, toaster, microwave, blow dryer, tea kettle etc and may be only to operate 1 high draw item at a time.
most of us have 2.8 kw onans which translates to about 20 amps of current ( 23, but allow for switches and resistance in the wiring)
the onan rating is at sea level, at elevation the thinner air will reduce output. as I recall I think mine is closer to 2k at 6000 feet
many onans have an altitude adjustment lever on the carb to help the motor run better, but the thin air just doesn;t allow the motor to make as much horsepower