Since I am not aware of any remaining major issues, it is time to set this as the first production release. Except for minor metadata changes (screenshots, minor description changes), there is no difference to the test version 0.19.
If everything works out, I am aiming to release this together with the blog post about using broadcast intents on the Play Store on Saturday (7th December) and share it with a wider audience with a Youtube video. (Of course I cannot control the exact release time for F-Droid, but it should be similar unless something unexpected happens.)
Many thanks to everyone who reported issues and helped to fix them!