On F-Droid, there is an app FFUpdater. It checks for new apk versions of various forks of Firefox and updates them (automatically or by notifs, user preference)

On F-Droid, there is an app FFUpdater. It checks for new apk versions of various forks of Firefox and updates them (automatically or by notifs, user preference). I guess you could fork it and change the apk it searches for - you'd end up with something exactly like what you want. N.b. i haven't looked at the code, maybe it's a rats' nest. But i'm optimistic given the simple domain. :)