F-Droid which is an open source alternative to Google Play that only contains FOSS (Free and Open Source Software) apps.
F-Droid utilizes something called repositories. The official repository is very strict about which apps can be included so you can add other repos to get more FOSS apps. Izzy's repo is a popular one.
If there are some apps that you can't replace with FOSS ones and need Google Play for that then you can just use Aurora Store. Aurora Store is a FOSS client to access Google Play without an account.
What are some of the FOSS apps you use and would recommend? Oh and how do we feel about a FOSS comm? Here is a request for one
Moxie has been pretty consistent that he wants Signal to stick with G services (though it should work without now ) and doesn't allow (as much as he can) forks of signal and does not support federation .