I'm great on a mountain board. I built my first one from parts on the internet in the early 2000s. No brakes on that one. Broke my collar bone on it. I can ride one on the trails anytime I want. But the onewheel is a better experience. Mountain boards have 4 wheels, and are infinitely less agile on rocky trails due to this. The 4 points of ground contact create constant instability that is limiting compared to a onewheel.
By the way, I do a ton of riding on Jeep trails and roads as well. But the challenge isn't on par with single track.
The intention of banning "motorized" vehicles was never about the power source itself, but instead the negative externalities created by the power source. It was about preventing the negative externalities that "motorized" created in decades previous to the current one, when virtually every motorized vehicle capable of being on a trail was powered by an internal combustion engine. With ICE, you have to have a ton of horsepower (compared to EVs) to get enough torque to handle trails. There was no such thing as a "motorized" vehicle that was silent and non-polluting. They had top speeds in the 40s and up, and due to the engine are hundreds of pounds and therefore dangerous, on top of the noise and exhaust.
You've ignored the "spirit" of the law, or the reasoning behind why they were put in place. You've fixated on a technicality, out of a misguided sense of purity, where everyone on the trail needs to "earn" the right to be there through direct physical effort. The people who banned mountain bikes had the same argument as you, viewing any form of wheels as "cheating". It's a quasi-religous viewpoint, it's not logical, and therefore you are forced to resort to technicalities without explaining the logic of how a onewheel makes the trails less safe, less intact, noisier, less hospitable to wildlife than a mountain bike does. You have no answer to this. Instead of examining your viewpoint, you stand on the letter of the law. It's a sign of a very weak position.
> You're just selfish and disrespectful of public lands.
Please name a single way I am hurting anyone else on the trail that differs from a mountain bike. Name a single example. What does my onewheel do to interfere with other people's use of the trail that a mountain bike doesn't? You may have an extremely insightful point that I haven't thought of. If you do, it might change my mind. I don't have any desire to "disrespect" public lands, or hurt others. How am I hurting others? How am I hurting the trail?