You are a daily power user who watches live streams, wants 4K, uses YouTube Music, or relies on casting. In that case, spending $30 on a modern streaming stick is a better long-term investment.
If no apps work, the most reliable way to watch YouTube on Android 4.4.4 is to use a web browser (like Chrome or Puffin TV Browser) and navigate to m.youtube.com How to Install an APK on your TV: YouTube Not Working on OLD Smart TV 4.4
The official YouTube for Android TV app is with Android 4.4.4 (KitKat) as modern versions typically require Android 8.0 or higher . The last official versions that supported Android 4.4 were released around late 2019 . Latest Compatible Official Versions
Go to Settings > Security and toggle on "Unknown Sources" to allow APK installations.