Go to your phone homescreen and look at the app dock (the bottom row that contains some apps and stays the same when you switch pages).
Which are yours? Any FOSS apps?
In my case, they are FDroid, Signal, Threema, Firefox and the defaul Samsung camera app. So, 80% FOSS…
Molly-FOSS is the fully FOSS, hardened fork of Signal that is available on Fdroid via their repo.
Here’s a feature comparison on their github between Signal, Molly, and Molly-FOSS. Basically, the stock signal app relies on some google services, Molly-FOSS does not.