It works like a charm for us. We've also tested if we could create enketo links if our api key in Central is different than in Enketo. The result was: no.
We've also removed the secrets from the docker volume, so we won't lose them if sbd. accidentally executes docker-compose down.
As far as I can tell there is currently no technical obstacle anymore to provide pre-build docker images. If you are interested, I could make a PR with a new setup.