Dual Fuel Generator: need both?

Please let me know if there is a better place to post this, looking for broad knowledge!

I am considering buying a generator for 'glamping' and and emergency preparedness (in a seismic zone). I already have a lithium PSU (since the glamping use case means I can't use the motor genset when I need the power). Absent the emergency prep, I'd live with the lithium unit (1.5kW/1.2kWh).

I would really like to avoid gasoline appliances, but generators seem to be either gas or dual (gas/propane). Agreed that for EP, handling both is a plus.

Looking for experience with this (and advice about "should I run it with gasoline every so often...?").