Youtube vanced, no jailbreak needed, been using it for months, has both things you ask for and more.
Switched from iOS to android and i missed my youtube++ app that was on my iOS where I can watch videos without ads and in the background. is there any similar tweaks for android?
assass1nator (06-12-2019)
newpipe is exactly what you're looking for.
youtube vanced has background play, no ads. to use your google account(for subscription etc) you need microG. Just google youtube vanced and go to their official website(not the xda one) and it'll explain everything
newpipe to download videos/audio
As I have iOS I use youtube ++ but I heard that Youtube Vanced for android is decent.
Youtube vanced is the best.