These things popped up on the radar a couple of years ago in Australia, causing a lot of emotion and opposition sentiment from mtbers, myself included.
There were one or two spotted around the place, riding on mtb trails. It was made pretty clear to those who had them that if they were seen on approved singletrack they would be detained under citizen’s arrest until the police arrived, for riding unlicensed on an unregistered and uninsured motorbike. (The power limit for electric assist here in Oz is 250w, a tiny fraction of the 3,000 or so they brag about in their marketing crapola.)
That never happened, since they’ve pretty much sunk without a trace.
Those bogans preferring motos will spend approximately the same money on a moto, and get much better performance. Those preferring to get some exercise will buy a pedal bike.
A solution in search of a problem. I doubt you have much to worry about.