A 12v power inverter can be useful in a small off-grid treehouse when the goal is to run basic AC loads from batteries instead of starting the generator for every light or charger. It should be fine for modest devices, but higher wattage loads will pull serious current from a 12V bank. That means cable size, fuses, breakers, grounding, and battery capacity all need to be planned carefully. I’d size it around actual daily use and surge demand, not just the advertised watt rating.