@Tourma

Cromite seems to be a good browser for Android (though not Gecko-based)

It's a fork of (the now discontinued) Bromite, which was a fork of Chromium without Google but with several privacy and security improvements

I don't know how many maintainers Cromite has, but I've installed it in summer and it seems to be updated at least once per month

It's on F-Droid, too

https://www.cromite.org