Hopefully Mozilla takes security seriously with mobile Firefox, finally. Otherwise Apple will appear justified in their regulations. The Android version of Firefox doesn't even support IsolatedProcess yet.
The Android version of Firefox does support NoScript and ad blocker extensions, though.
Releasing it on iOS would be huge. No more almost-functional Safari ad blockers with multiple pricing tiers! No more all-or-nothing JavaScript toggle button!
Honestly, the only thing keeping me from iOS is its inability to run a browser with a decent extensions ecosystem.