What about HTTP/2 Multiplexing, how does it hold up against long-polling and websockets?

I have only tried it briefly when we use gRPC: https://grpc.io/docs/what-is-grpc/core-concepts/#server-stre...

Here it's easy to specify that a endpoint is a "stream", and then the code-generation tool gives all tools really to just keep serving the client with multiple responses. It looks deceptively simple. We already have setup auth, logging and metrics for gRPC, so I hope it just works off of that maybe with minor adjustments. But I'm guessing you don't need the gRPC layer to use HTTP/2 Multiplexing?