Gadgetbridge just doesn't do it. Nothing is sent, and I can't update my watch face.
I found this page: https://github.com/Freeyourgadget/Gadgetbridge/wiki/PebbleKit-Android-App-Compatibility and "Notification Center for Pebble" works great. This you can find and install from the Aurora store.
Also a reminder to NOT USE THE F-DROID STORE. Use something like "Droid-ify", otherwise you will not have access to notifications.