This approach deeply resonates with me. The only thing missing is maybe a GPS tracker thingy. But I am not sure which usecase this would have. Maybe not having to call my child when they are late but instead looking up where they are.

The missing Parental controls for Unix should actually be pretty easy to implement. When the time comes there will be either a useful one present or I will write an increasingly sprawling cronjob to approximate the job

Teach them how the bad tech works so they naturally avoid it. Teach them how good tech works so they naturally reach for it.