Hello , so no one is allowed to drive with this device on German roads, the road approval applies to other European countries. In Germany, the s1 and the pro2 would be suitable, it can be "approved" by many insurance companies (mainly liability is covered, costs 20€ a year and you get a sticker as a number plate). Your son is then allowed to ride it without a moped test certificate "but only on a bicycle" for riding on pavements etc. I had to pay 60€ myself. I had to pay 60€ myself 🤮 have fun riding 🙋♂️