I really feel very uncomfortable with the notion of tracking the kids anyway. Arming them with knowledge as best as possible, and as usual showing interest in their behaviour to try and look as best as possible for signs of problems but ultimately kids are still people with their own lives even if people in development. Yes you need to protect them, to a certain extent, but ultimately some of this is no business but their own. You can try to educate and forewarn and hope some of it sticks but the tendency from my memory of being a kid is that that tends to be met with an eye-roll, this is probably where the temptation comes from to track children or drastically restrict the choices they're able to make so they can't ignore you but this is hardly a great way for that person in development to ultimately... develop.
This is dicey though, not least because as yet another random person on the internet offering their unsolicited opinion, I don't even have kids, and if you follow my logic to extremis, you basically have, "let the kids just figure it out on their own they'll be fine" which definitely won't apply to everything and can have disastrous consequences in some contexts. But nevertheless I think this concept of tracking, either covertly, or overtly with the intention of making a kind of panopticon effect for the kids, is likely ineffective but even if effective, is indicative of something going wrong with the intent of the surveillance.