@Billie I agree. Recently I have pulled my watchface from the Google Playstore. They were constantly nagging me that something was wrong with a screenshot, but didn't explain what. After a couple of resubmissions (all rejected) I eventually gave up.
I have to find out if watchfaces are suitable for F-Droid. But I won't publish any non-commercial apps at Google anymore. It's a waste of time.
@shred if you can give me a link to your repo with the sources, I can take a look. "Watchfaces" is a bit generic; F-Droid.org might be unable to add it if they are using Android Wear (proprietary), for example.