Oh, now that sounds cool

At this point, the last thing I need is another generator --- I've got a 5kw construction open frame, a Yamaha 2800, and a Honda 2200. But I'm always curious about things like this and I'm still not sold on battery solutions
The smallest genny I've ever seen is the little
2-cycle generator that harbor Freight for a hundred bucks and was identical to about a dozen other companies. It worked great for what it was.
We ran a concession tent with it for a couple of summers. It sipped gasoline (though it was 2 cycle, so you had to mix oil) and never missed a beat. We ran it for hundreds of hours and being 2 cycle it was literally maintenance free except the air filter. I gave it to a friend for his emergency use, and to the best of my knowledge it still works. You just needed to run it for a few minutes every few months to keep the gasoline from varnishing and gumming up the carb.
The 2 small inverter generators I have are equally reliable but take oil changes yearly or after extended use.
I'm from the hank hill school of maintenance --- I change the oil every 25 hours or I get bored whichever happens first.
The recommend 100 hours (after the initial 20) --- so mine ought to outlast me. I just don't want to be sitting a 90 hours on the clock, to have the lights go out and not be able to change the oil on time. If I change at 25, or even 50, I have 50-75 left on the oil. Using synthetic, I've still probably got a lot of life left...Oil is cheap -- engines aren't.