I read the "The drive system is composed of a small generator, a 250-watt wheel hub motor, a lithium battery, and a control unit on the handlebar." and think I have a 350 watt peak, 250 watt continuous rated hub, and I have pedal hard to get up hills.
There may be a version I am unaware of, but in the main it is considered the extra weight required to get regenerative braking will need more effort to get from A to B than it is worth.
However the big hurdle is the law, be it a scooter, skate board, or bike, once one adds a motor it is the legal bit which stops progress, this is why UK excelled over France in the early days of steam, the French government made it hard for the engineer to progress.
Before the law insisted it had to be propelled by pedals, with only electric assist, we had electric scooters in style of the old mods era which were legal on British cycle paths, even today the law is rather vague, 250 watt on a continuous basis, what is continuous? Clearly a 1000 watt motor is not legal on cycle paths, but 350 watt peak, is it or isn't it, I would say legal, but no one can say what a court would say.
So taking it to the silly stage, you sit on an exercise bike, which charges up the battery on your e-bike, then use the e-bike. There is no way to prove you used manual labour to charge the battery, so still limited to 250 watt.
I find I need to be doing 3 MPH or more to balance, under that it is walk assist. It does not matter what gearing you have, with a 22 stone body you can't get up a 1:6 hill with 250 watt.