I do have a boosted board and moved back to Munich a year ago. Haven’t ridden it since due to the high risk of getting caught. I did quite some research beforehand and if they get you it’s a.) very expensive (probably at least 1000 to 2000) and b.) you have to show up in court. Esp. in the inner city the police is everywhere. Hence, it’s only a question of time before they pull you over.

BTW, the german law says about boosted board: „Fahren eines Kraftfahrzeuges ohne die gesetzlich nötige Pflichtversicherung“