Out of the box it can play audio in the background, and now that extensions are available you can block ads as well. You don’t really need constantly updating 3rd party clients or questionable firewalls anymore if you just want usable youtube on a phone.
AdBlock was on mobile for years. One of the few add-ons that worked.
I’ve used almost all the addons I have on desktop for years with an extension collection and FF nightly.