My understanding is that Fennec only removes Mozilla’s telemetry, whereas IronFox (forked from the discontinued Mull) is that plus patches to further harden the browser.
IronFox is available through F-Droid via the project’s own repository, but is recommended to install through Accrescent, which you can learn more about here.
Why not fennac straight from F-droid?
My understanding is that Fennec only removes Mozilla’s telemetry, whereas IronFox (forked from the discontinued Mull) is that plus patches to further harden the browser.
IronFox is available through F-Droid via the project’s own repository, but is recommended to install through Accrescent, which you can learn more about here.