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.
I can recommend Orion Browser. It’s from the people that make Kagi. It has the option to either install chrome or Firefox addons. Syncs across iCloud also.
https://kagi.com/orion/