Forgot to mention: Firefox for Android hates adoptable storage. Not only does it "not know" about SD installs (like Metal and Relay), if you reboot your phone for any reason, Firefox will be completely missing when the phone comes back. I had a home screen shortcut to Firefox, but it'd change to a generic Android icon after reboot, and that was the only trace of it on the phone - it was missing from the app drawer and Settings > Apps. I actually loved Firefox Mobile, because of the "open later" and uBlock extension... but just gave up on it after all this BS.