Drop it. It's a gordian knot. You have 25+ different jurisdictions. Some are very harsh on privacy laws. The problem I see with your application is the consent

Drop it. It's a gordian knot. You have 25+ different jurisdictions. Some are very harsh on privacy laws. The problem I see with your application is the consent. You need specific consent by a party, say it's a legal guardian. I'm not sure if legally, in all EU countries, a parent can monitor a 16 or 17-year old's mobile. What happens if a parent installs your app to a 16 year old and leave it there when he turns 18? From what you're saying it's not even worth pursuing, I mean you basically need a expert's law advice in every one of the 25+ EU countries.