I'm not sure about other states, but in CA you still need a special license, the same as a motorcycle, to ride a moped. I'm sure this would be the biggest blocker.
https://www.dmv.ca.gov/portal/dmv/detail/motorcycles/motorcy...
A motor-driven cycle has 149cc or less engine size. CVC §405 A motor-driven cycle has to be registered and the driver must have a motorcycle license (M1).
For electric mopeds, it's based on horsepower, not engine size.
They do recommend an in-person training course, but you can also simply watch a series of videos on their app, no special license required.
But you can't drive it on the interstate and most major highways, for obvious reasons.