I have used my battery saws in response work. It is helpful to have multiple battery packs, but we normally have electricity for recharging at night. We typically also use battery powered drills, recip saws, and other tools.
They can be really good for ‘grab-and-go’ tasks: small projects, or while the other guys are getting set up.
They can travel in the passenger compartment of a personal vehicle (no flammable fuels) if a group splits up.
And they can be good for training new volunteers, focusing on things like cuts, binds, safety, etc., without the noise of a 2-stroke saw, or with people new to operating gasoline outdoor power equipment.
Philbert