Jellyfin + ytdlp + playlists = pretty good, in general. and avoids ads; the ads are worse than almost anything else you can find.
No need for manual ytdlp! I use TubeArchivist[1] to download channels and then share them with kid's account on Plex. I'm surprised it hasn't been mentioned yet. Great self-hosted solution.
If it’s just the ads that are the issue, paying for YouTube premium would be a similar cost solution, and funnel some money to good creators.
Towards a better Jellyfin solution, I wonder if adding Whisper and an LLM model could transcribe the YT videos and flag any which contains themes that go against parents values.
Do you have any automation on ytdlp and Jellyfin?
I built this with Jellyfin and Home Assistant for my kids: https://github.com/philips/homeassistant-nfc-chromecast