These solutions exist, why would you expect Blink to try and reinvent the wheel.
Loads of them, readily available, for around £100. Some much less, some much more. You get what you pay for. Do your research beforehand, test fully on receipt, and return if inadequate. Some are very very good. I have one hidden in a quad bike, and the amount of information I can get about its location, or history, is astonishing. GPS geofencing, speed limit, vibration alert, and a whole bunch of other things can all be set and managed. Only cost £40. Maybe a little large for a child, but still, it would easily slip in a pocket. Batteries last 6 months on a charge. What more could you be wanting?
Not sure what any of this has to do with Blink?