I think i have a decent checklist of things to work on and my thoughts, let me know if there is anything else missing 
- Open video in youtube.com (Share button)
- Share video URL button (same button as above)
- pagination of history results and of in general to limit wait times (it seems to load the entire history in one chunk, bad.. maybe use long lived cache too.)
- Subtitles and auto translate
- Selectable audio track and auto dubbed tracks
- Login support and import subscriptions from youtube (same as FinTunes cookie import, import playlists too?)
- BUG with BT crashing the app when BT is disconnected (needs testing)
- Regarding login, support for “Premium qualities”? (I dont have a premium account so un-testable from my end, but sounds like another itag that is available when correct cookies are supplied?)
- Settings toggle for enabling portrait fullscreen mode.
- Rename import subscriptions to “Import from newpipe” or “import profile” something like that
- Filter shorts in subscriptions feed (probably slow due to having to query every video)
- unify cache, set better TTL (Avatars and such dont change often so there is free optimizations there)
- remember speed set during playback function (set in the video player or in settings? not sure.)
- some sort of tutorial on how to use the app? (or maybe the app is obvious enough as is?)
- internal stream error is an issue that the “recoverer” should handle automatically (but it doesnt always work, swiping out of the video and back usually works better. look at why?)
- De-clutter the resolution picker in the video view, takes a bit to scroll all the way up to the download options (Button perhaps)
- Livestreams work but it isnt clear if its a normal video or a livestream (maybe a “LIVE” tag works)