> unless it is a prioritized, canonical implementation it will be missing things
Perhaps. But for now, such canonical implementation (I assume you are referring to the Go one?) is painful to access and has all around really bad user experience. I'm simply pointing out that more ecosystems could learn from .NET's example (or just adopt it) rather than continuing to exist in their own bubble, and more engineers could have zero tolerance to the tooling with bad UX as it becomes more popular.
Now, with that said, I do not think gRPC is ultimately good, but I do think it's less bad than many other "language-agnostic" options - I've been burned badly enough by Avro, thanks. And, at least within .NET, accessing gRPC is even easier than OpenAPI-generated clients. If you care about overhead, Protobuf will always be worse than bespoke solutions like RKYV or MemoryPack.
I'm looking forward to solutions inspired by gRPC yet made specifically on top of HTTP/3's WebTransport, but that is something that is yet to come.