I always wondered whether local logging is an option. Everything little Johnny does in his iPhone gets recorded and sent to dad’s MacBook Pro for processing every night. A local process looks for anomalous content while also producing a report of all sites visited and apps used. Taking a screenshot every 5s is going to be ~1GB per day but maybe Johnny doesn’t get to use his phone until yesterday’s log has been processed?
Perversely, to configure such a system you would have to actively prove you were doing so for a minor. You wouldn’t want to enable adults monitoring other adults.
If I worked at Apple this is something I would actively want to build, if it wasn’t there already. Anything to undercut these thin-end-of-the-wedge big brother bills and take the wind out of the “think of the children!” content authoritarians.