I have experience doing so with .NET simply because writing RPC / Contract definition in a .proto file once and then having gRPC tooling generate all boilerplat

I have experience doing so with .NET simply because writing RPC / Contract definition in a .proto file once and then having gRPC tooling generate all boilerplate associated with it is much better than dealing with existing OpenAPI generators - this one slots right into .csproj where you just add a package reference and a reference to .proto file and you are ready to go.