Codable support would be very useful. Codable is really the way to go nowadays with data models, rest apis, etc… There seem to be some promising work at GitHub - couchbaselabs/couchbase-lite-swift-coder: Data Model using Encoder/Decoder for Couchbase Lite Swift, but should be put into the main repo, as it has dependencies on the main repo and therefore is much less flexible for importers than being integrated and supported in the main repo.
This will be integrated into the official repo when we officially support it. Unsupported projects are available as open source projects that you can use and contribute to.