My kid is still too young for YT and I’m not sure what age group you’re targeting but there’s a huge mass of people that do not like YT for the early years. And try to avoid it for as long as possible. I think this is a niche to tap into if you are interested in monetizing this as a better experience for these types of parents. This could be the toddler to 10+ just whenever parent decides to allow it but wants to do it in a controlled way. I don’t know if I’m in the minority, because I’m kind of in a bubble (fancy private school environment), but a lot of the other parents I know are YT-free homes and even iPad free but that’s at age 6 right now. I’m hoping to stay away from it for at least a few more years with my son. Anywho.

I’d definitely use an app that gave the kid recommendations and some discover-ablilty that the YT algorithm provides (probably with some more pre-filtering) except just as tiles/gifs previews and they had to “request access” to any video to play. Or have some redefined categories as you mentioned. Then once a video was allowed, it would appear as available in the app via yt-dlp or similar.

This does 2 main things I prefer as a parent. I get control over the content. It removes the instant feedback /random access loop of on-demand streaming. For some things it might even be good to control how many times they can watch it , or if they have to ask permission again, etc. Not sure if you could bolt on / use as a base but this kind of customizations for stacher would be perfect.