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…
Woohoo! Nice going. How are you liking Librera compared to FB Reader?
So far its a pretty solid replacement. Though searching network libraries could be better. As far as I can tell theres no actual search feature.