This is a list of THE BEST FOSS apps with those criteria:

    Open Sourced
    Free of charge (on F-Droid and source code repository releases)
    Free as in Freedom
    Ad-free
    Installed and tested by me or by contributor
    Privacy-friendly aware
    Easy to use
    Still in development or polished experience
    Does not lack features compared to proprietary app
    Does not need an account (the only exceptions are self-hosted apps)
    Has dark theme

AWESOME apps counter: 267