It can be a bit buggy at times, but when it comes to just playing music with the screen locked, it’s perfect.
https://addons.mozilla.org/en-US/firefox/addon/video-background-play-fix/
Edit: I forgot to also mention that ad blocker extensions make sailing the seas on mobile much more manageable. Extentions, in general, have been a really nice addition.
And for everyone else who doesn’t want extra garbage on their phone it’s: switch to ‘Desktop Site’ > continue doing whatever else. This applies to both Firefox and Firefox Focus
No need promote/install more unnecessary stuff on your phones 🤦
Edit- that being said, I still include no script/ublock in FF and use FFF for yt videos when I don’t want to clog my Tubular history (newpipe fork with sponsor block) with useless stuff that I’ll never want to rewatch.