I think DudePerfect have an app that is essentially this. Heavily curated kid friendly content. It might only be paid though.
Yup - our kids use it and it’s the only “YouTube” kinda thing that’s worked for our family.
I had a look, and it seemed to be just their content? I thought the GP meant an app with a range of content.
They have their stuff and, I’m not sure how to word it, but like affiliated channels or other channels within their “network” - such Ryan Trayhan (my spelling is off there)