Great writeup! I use Firefox as my primary browser on Android (although I’ve started using Brave browser too now). I think FFOS showed the way, like the Nexus devices for Google, and maybe both projects are no longer needed now. I REALLY REALLY LOVE Progressive Web Apps, and combined with all the new APIs, really all that would be needed to make Android a “Firefox phone” would be a good launcher/home screen.* I hope we see more and more integration of web apps into all the major OS’s.
*Literally coming up with this idea on the spot as I type, but… what if FF (the browser) supported Android’s “home screen” API so when you hit the Home button, it was possible to select Firefox as your launcher? You can launch most apps with specially formatted URLs, so it might be possible to even implement the launcher as some kind of dynamic bookmark folder.