It would be cool if there were tiered parental controls on fedi for running localized kid safe instances.
You could run a local instance for a school or whatever and initially let the kids only talk to each other then slowly let them out to access a list of safe instances as they get older and learn more about internet safety. Might teach a healthier relationship with the internet.
Hey that is a crazy idea, because that would paint a target on those kids
I think you captured the challange well. In the physical world we build kid safe places and they come with some of the same challenges.
No solution will be perfect, but your idea is better than just saying "good luck kid". You would need a stong safety approach, but lots of people like helping kids so it may be easier to get helpers and mods (lots of vetting would be needed)
EDIT: because there are many different parenting styles the fediverse model may work well. Parents can pick an instance that matches their style.
That might work with schools and school divisions working together where everyone is the same age.
Beyond that, it is a terrible idea because certain instances will be known to homes to minors.
The fediverse is anonymous-ish, but not completely.