Comment by cyberax

You can easily do this. Protobuf supports pluggable writers, and iterating over a schema is pretty easy. We do it for the JSONB.

I'm not sure the purpose, though. Protobuf is great for its inflexible schema, and CBOR is great for its flexible data representation.

A separate CBOR schema would be a better fit, there's CDDL but it has no traction.