F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
Something worth noting is that F-Droid is both an app to download other apps but they also maintains a repository of apps. You can use alternative store apps (like Droid-ify) with the F-Droid repository OR you could use the F-Droid app with a different repository (like IzzyOnDroid). You can mix and match to meet your needs.
I use the Droid-ify app with the F-Droid, IzzyOnDroid, microG, NewPipe, and Collabora repositories.
Once you start down this rabbit hole, give Obtanium a look.
Something worth noting is that F-Droid is both an app to download other apps but they also maintains a repository of apps. You can use alternative store apps (like Droid-ify) with the F-Droid repository OR you could use the F-Droid app with a different repository (like IzzyOnDroid). You can mix and match to meet your needs.
I use the Droid-ify app with the F-Droid, IzzyOnDroid, microG, NewPipe, and Collabora repositories.
Once you start down this rabbit hole, give Obtanium a look.
I second Izzy, add:
https://apt.izzysoft.de/fdroid/repo