I believe YouTube Terms of Use prevent anyone from making third-party youtube app on iOS. Android is maybe another story because you can sideload.
https://developers.google.com/youtube/android/player/
https://stackoverflow.com/questions/4654878/how-to-play-yout...
Now, I would just have to see if it is possible to only show certain videos or a range of channels.
I believe YouTube Terms of Use prevent anyone from making third-party youtube app on iOS. Android is maybe another story because you can sideload.