VerPoilu

Do you need a license plate and (I suppose, depending on the state) a helmet for those bikes as well?

This kind of e-bike is not allowed (or it is, but with big caveats, more akin to motorcycles) on public European roads. Regular ebikes can't have a throttle and are heavily restricted on top speed (20 to 25km/h depending on the country. Can go faster but you're not helped by the motor over that speed).