If you get the Hybird it comes with a 2.4kw generator. It is standard. Costs you nothing if you are buying the truck anyway.
At 400 watts the truck doesn’t even start. It runs when it needs to charge the battery with its 35kwh electric motor/generator. The battery on the f150 is 1.5 kwh so it would hold a load of 400 watts for a couple hours with just a few minutes of total idle time if any depending on the state of charge of the hybrid battery.
On the TFL video with the 7.2 kwh generator charging a car the truck shut off with 2400 watts on the generator because it didn’t need to idle to keep charging
The write ups I was reading on the hybrid F150 showed it a very desirable rig. If I had the money I would buy one. They were giving the caveat that the generator feature alone was not the reason to buy it. For longer generator use the portable Honda was far more efficient.