I wonder why these FOSS-y projects don't bundle Firefox for Mobile with them. It is a far superior experience with Add-Ons. In fact, I don't even use most apps

I wonder why these FOSS-y projects don't bundle Firefox for Mobile with them. It is a far superior experience with Add-Ons. In fact, I don't even use most apps anymore, most websites' web versions are more than adequate nowadays. In fact at least in one instance viz. Duolingo, the web experience is far superior than the app.