As for the OS: any usable version of Linux will do. The thing about computers for kids is that they won’t learn anything if you don’t give them the real deal. Unless they’re 3 years old, I would stay away from the kiddie Linux distros. Chances are they won’t need to install much.

I was able to use a computer when I was 10 years old and that was full fat Windows XP. Taught myself Windows 98 and 2000 in English not long after. The generations before me were programming in a command prompt around that age, if their families could afford computers of course. The eighties proved that ten year olds can teach themselves assembly if they’re motivated, you don’t need to dumb things down for many kids.

Parental control is a problem, though, specifically the online stuff. Various distros offer various amounts of control but I don’t think anything comes close to what proprietary tools offer. Even proprietary tools can’t monitor Discord calls or detect suspicious Snapchat messaging, though.

Your best solution here may be to go full Windows 11+Microsoft everything; Microsoft’s parental controls work pretty well and they don’t require installing some shady third party tooling. In my personal experience, being able to work Windows will transfer pretty directly into being able to use Linux.

The best defence you may be able to mount, long-term, would be some network intelligence tooling to detect what kind of websites are being visited (DNS traffic ) and detect basic circumvention techniques (DoH, VPNs). I believe the most important part is that you don’t make a secret out of the fact the computer is monitored, that you gradually reduce restrictions over the years, and that your kids can come to you with any question or bad experience without fear of “punishment” in the form of stricter monitoring. Nothing creates distrust like finding out your parent is reading your messages or the idea that they will isolate you from your online friends when you’re found out.

What you could do, is configure an old, second computer that can’t go online with Linux and tell your kids to go ham. With some additional setup for snapshots and such (on either Windows or Linux), you can recover from almost any failure, so you can even give root access without too much risk.

Put some games onto it, let them mess around, under the understanding that only the more closely monitored Chromebook/computer/smartphone/tablet is allowed to go on the internet. That way, the kids can have a space of their own where they can explore computers in general risk-free, while you can guide them in the online stuff. This can be as simple as using an old desktop without a WiFi card that you occasionally plug an ethernet cable into for updates. You may need to work out some compatibility mess if you go with Linux, but if you use Steam you should be able to load decades of games onto that thing for cheap, more than enough to keep kids occupied I would say.