“Pure” LineageOS 16.0 (without GApps, without mircoG) now runs on phone S5+
F-Droid with FOSS (Free and Open Source Software) is used as the only app store - plus apps that are subject to an open-source license.
You can use AlternativeTo to search for Apps for Android with Open Source License.
I assume that there is no app of daily use that I could not replace with a free alternative.
Minimalism via LineageOS: Less is more … as a long-term test next to /e/ OS.