For quite some time now, I do not only use LineageOS (previously CyanogenMod) on my smartphone but, for very few exceptions, I also only use open source applications from the F-Droid app store. What I only recently learned, however, was that all applications offered via F-Droid are compiled by F-Droid out of their respective repositories.
The F-Droid app developer FAQ states the following:
Will my app be built from source?
Yes. In all but a very few cases (for technical or historical reasons), we build all applications directly from the source code. This guarantees that the source code is available for the version people have installed. While we’re not suggesting that your source code is incomplete, not published or out of date, this happens a lot.
So this is the reason why sometimes, apps appear in other app stores (e.g. Google Play) a few days earlier as they just use the pre-compiled apk, To me the extra wait is well worth it, as knowing that an independent party has compiled the app confirms that the code that’s on Github or somewhere else is actually the real thing.