I would like to present gin-tonic to you. A work in progress prost replacement that allows you define transport representation for more types than just the protobuf primitives. It is compatible with tonic, therefore the name, cause be honest, what is best paired with tonic?
https://crates.io/crates/gin-tonic
The basics should be working. I know that maps with messages as value type are not yet working (at least from code generation site) but i'm aware of this and try to fix it.
Let me know your ideas or give it a try.