I’m not sure exactly how far back you need me to go:

1. Mozilla made Firefox for Android
2. Divested Computing Group (developer behind DivestOS) forked it into Mull (which is completely unrelated to Mullvad)
3. The privacy community largely considered Mull to be their mobile browser of choice due to its out-of-the-box focus on privacy
4. Just this month, Divested Computing Group announced that they will be ceasing development on all of their projects
5. IronFox was soon forked from Mull, aiming to continue its goals of focusing on privacy
6. Until now, the only official way to install IronFox was by downloading the APK directly from their git repo (or building it from source, I guess). Now that the developer has set up an F-Droid repo, one can add that repo to their F-Droid app and allow F-Droid to manage downloading/installing/updating IronFox