[MathMonkeyMan]

I don't have kids, so I really can't comment, but I'll describe my setup.

Ublock origin and Sponserblock on Firefox. I also have an extension (forget the name) that blocks recommendations after a video. Disable autoplay.

There are also extensions that replace the home page with the subscriptions page.

But really, if BS exists on the internet, either your kids will find it or it will be shown to them. There's nothing you can do.