I’m going to go out on a limb and assume OP is similar to all of my friends and missed the fact you can manually curate yt kids? Yt kids is also odd because you need to be signed in as the parent and the kids account isn’t its own independent account.

Perhaps this solves the fatal flaw that your kid has to have your google account signed into their tablet to watch yt kids. I got my child their own tablet, created a child Google account, signed into the Android tablet with it, and then I was unable to restrict what they watched. Best I could do was the young child algorithm, but there’s still so much trash.