True hacker kids will figure it out no matter what. If the phone is restricted they will jailbreak it or beg an old one from a friend. If the network is locked down they will crack the password for the neighbor’s wifi. If the clearnet is locked down due to authoritarian laws, they will end up on incredibly sketchy sites on the dark web. If you block all escape outlets they will do really stupid things in nihilistic protest like huff cans of whipped cream or scam money from crypto. The power of bored youth springs eternal.
What I’m saying is you can set rules, you can try your best, but under no circumstances can you build an impenetrable wall for determined kids. Things like this header solution or better controls on the end device would make things safe for the vast majority of kids. So don’t ruin the internet for adults because of a handful of unruly kids who are going to get in trouble no matter what.
Walls don't deny access, they change traffic patterns. A header can be honored on a phone designed for a child and ignored by my phone. Can some kids get through, sure. But not the vast majority. If people were honestly doing this for kids, this would be the solution being pushed. This has nothing to do with kids, hence other types of solutions being pushed. Don't trust what people say, observe what they do.
I remember when I was around 11-12 years old, my father got me a computer given to him for free. It had only a console and a black screen, and I figured out by myself how to open, edit files, lock them, navigate the file system, run programs like a calculator and more, with no manual, no internet, and I didn't even know english good enough.
1-2 years later, the teacher at school showed us how to program the turtle program, and I got it stuck in an infinite loop in 10 minutes. The teacher started swearing "Your chair is smashing the ethernet cable. The program is good and you fucked it up."
Around that time, I remember going to a barber shop for a haircut and stealing his nude/porn magazines. Even younger, I used to sneak up to my uncle's bedroom where he hid alcohol, and drunk half a bottle of whisky in an hour, and getting knocked out every time.
I used to get involved in fights all the time, since 8 years old, and my favorite activity at that age, was to climb to roofs of abandoned houses at night, and wander around inside of them.
My parents regularly tried to talk some sense into me, and I was beaten up by my father for all the stuff I did.
When I was sixteen, I managed to steal a car by myself, I drove it around for 1-2 hours and I didn't know how to drive, I figured it out at that moment. After that I returned the car where it was at the start, I didn't do anything with it, but when driving it I managed to flat the tire somehow.
When I was at the university, at some point around 20 years old, I downloaded Kevin Mitnick's book from torrents, I read it, and I got inspired to phone to my university, pretend I am a professor and I want pass a student (me) for 2 courses. I passed the courses without even taking the exam.
It was around that time, a friend of mine, while he was playing the guitar at his house, he looked at me at the eyes and said dead serious: "Man, if you go on like this, you will end up in jail." It was actually earth shattering! First time someone talk some sense into me. I thought, this cannot continue, he is right.
What I’m saying is you can set rules, you can try your best, but under no circumstances can you build an impenetrable wall for determined kids. Things like this header solution or better controls on the end device would make things safe for the vast majority of kids. So don’t ruin the internet for adults because of a handful of unruly kids who are going to get in trouble no matter what.