Your best bet for desktop is Librewolf, and for android is IronFox

I had to do a little digging but it seems that Mull has a spiritual successor in the form of ironfox for android. So far its legitimately good, just add the repository to your fdroid Link to repo:

fdroidrepos://fdroid.ironfoxoss.org/fdroid/repo?fingerprint=C5E291B5A571F9C8CD9A9799C2C94E02EC9703948893F2CA756D67B94204F904

If you read in between the lines, Mozilla is also funded by google as technical competition to chrome so that governments dont break them up with anti-monopoly busting case.