If it's any help, NewPipe [0] is a FOSS YouTube client for Android which doesn't require an account, doesn't require Google Play Services, and doesn't (!) display ads.
Yes, it has subscription support and you can import/export that list to keep it backed up.
It also has a TON of features, like PiP, background play (for video and audio), downloading, and much, much more.
Ivory [1] might be the closest iOS equivalent, and Motionbox [2] and FreeTube [3] the closest desktop equivalents.
[0]. https://newpipe.schabi.org/
[1]. https://apps.apple.com/us/app/ivory-video-player/id129434748...