F-Droid:
F-Droid is a robot with a passion for Free and Open Source Software (FOSS) on the Android platform. On this site you’ll find a repository of FOSS apps, along with an Android client to perform installations and updates, news, reviews, and other features covering all things Android and software-freedom related. https://f-droid.org/en/about/
I couldn’t find fennec or mull on the android app store, what are they?
Privacy-focused Firefox forks. You’ll have to get them from F-Droid.
Fennec:
https://f-droid.org/packages/org.mozilla.fennec_fdroid/
F-Droid:
F-Droid is a robot with a passion for Free and Open Source Software (FOSS) on the Android platform. On this site you’ll find a repository of FOSS apps, along with an Android client to perform installations and updates, news, reviews, and other features covering all things Android and software-freedom related.
https://f-droid.org/en/about/