

Google is not breaking the (German) law here, it actually is your responsibility as a user to not spy on people. Failure to do so means up to three years in jail, for a first offender most likely a fine. And your device that you used to break the law might get confiscated.
The later was already the case when people used radar warner apps (banned on Germany as well) and lost their smartphone for that.
No need to, there is no fruit of the poisonous tree in German law. Police can strip search you in bright daylight on a crowded square for no reason - clearly illegal, bit what they find will be used to proscute you. The officers will be punished as well, at most with a stern talking to.