• you can do this on desktop with freetube

    The settings you wold need to use are:

    • Password
      • Set a password for the settings menu
    • Parental Control
      • Hide Search Bar
    • Distraction Free
      • Hide Trending Videos
      • Hide Popular Videos
      • Recommended Videos
      • Hide comments

    probably still some edgecase ways to get around these that a dedicated kid could find but you can also ban videos containing specified terms and enable “Show family-friendly only” to limit what can get through even then.