True, a Goal Zero type “generator” ( and I agree- that’s a misleading term) is a stand alone battery that has a built-in inverter, but it IS easily integrated into 12VDC battery / converter and solar systems of our Airstreams as I and others have done. For older Airstreams, it is an easy way to get near seamless 110V outlet power anytime w/o firing up a gas or propane powered generator. Granted, one needs to keep power consumption in mind and I t won’t run for ever like your gas powered generator if you keep adding fuel to it.
Or set it outside and plug into it just like your 20 amp Honda, Yamaha, etc. Yes, it can be bit pricey, but more reasonable when a lithium battery, inverter, heavy gage wires, etc. and integration cost are considered.