Man I feel old and stupid, but really still not got it any further :( You made it even worse now.. "lives on the network.. without updating thousand binaries" - huh what, how?
You sound a bit like Urbit btw, not sure if appropriate ref though.
Everything is defined as protobuf interfaces, which is a standard used by Google and everyone else now that gRPC is so dominant. So the idea is, define the API in protobuf, code generate and implement the handlers for it. The service can be called by other services on the platform using that code generation and then an API Gateway, which Micro provides can be used to call services externally using the same format but using HTTP/JSON.
To take that even further, M3O (m3o.com) codifies protobuf to openapi specs and then generates client libraries on top. You can see some of that in https://github.com/m3o/m3o.