That seems like the best option. Adding a motor to a longboard is just enhancing a known proven quantity. It won't have the maneuverability of a onewheel or the all-terrain ability, but longboards are definitely a proven vehicle for roadways so motorized ones seem fine.

That or kickscooters, but they're not as compact as the onewheel or a longboard.

Fundamentally, the onewheel seems like a personal-mobility answer to the V22 Osprey: a vehicle with amazing functionality and versatility in its happy path, but is fundamentally unsafe in failure because of the basic physics of the situation.

edit: onewheel, not longboard, in the final paragraph.