As for me it would be really useful, I thought I share an idea for a nextcloud app to further get away from Google universe.
The android media player NewPipe is a nice way to watch videos from Youtube. Issue is that all favorites, lists and watch list is purely on my phone. But I watch Youtube videos on notebook as well.
It would be nice to have a newpipe server app that is able to sync data to my newpipe android app.