Second, it can be expensive and therefore not an option for everyone but there are schools with solid phone/media policies. My kids go to a school where phones are forbidden until 9th grade.
I wouldn't trust the general web to be age-appropriate for under-12s these days, including all advertising in any apps, but that doesn't mean I can't sympathise with parents desperate for some distraction.
My parents had it relatively easy with me: when I was five, I was using a Commodore 64, learning to read from its user manual and just starting to notice that the loading screens for some games counted oddly, going "…, 8, 9, A, B, …"
The worst that any of that meant for my parents was the incredibly minor point that that I was aware enough to notice the dual meaning of "Jet Set Willy".
With the right apps and restrictions, a smartphone is basically just a handheld console no different from a gameboy in functionality.
Unfortunately there is also too much pressure for constant analytics for me to feel at ease with the modern world, even in cases where I know from the inside that GDPR is being taken 100% seriously.
I'd be in favour of a change in the law such that analytics was banned, and/or software was required to function offline…
They also lean less on the parents when other kids are around because playing with other kids is what they really want.
When you look at the stupid videos, a good chunk of them give a sense of social presence. That's what the kids are craving. Pseudo-social media is a fake substitute, like artificial fruit flavoring.
My 8 year old has never used a tablet. He thinks phones are just to call people. He just knows that people use them for dumb things just because they can't bare to be alone with their thoughts for 2min.
Yes it is a "battle" and it requires time and effort. It's not impossible. Uphill battle for sure, one that I will probably lose, but still worth fighting.