Due to some interesting circumstances vaguely related to NFC I found myself having to set up an iOS device for my dad.
Now, he is a heavy user of NewPipe and downloading music from YouTube.
Just out of assumption I went and jailbroke the phone. (Just works! No computer needed, though you need to re-run it every reboot)
Now, searching though various places, there are barely any YouTube downloaders for iOS. (FOSS is already out the window at this point)
Found one, added the Cydia repo (back in the iPhone 4 days the default 4 was enough!)
It displays a banner ad on the YouTube app (not a 3rdparty ad network, so slightly better)
Nevermind that, lets try downloading something.
Oops no! You need to make an account with the downloader (wha?)
So I go do that, try downloading something, it works...
... but you cant seem to play it outside the (now modded) YouTube app.
Personal server. Totally overkill but ok.