It’s definitely on the roadmap. Out of curiosity, do you use client/server streaming or bidirectional streaming?
If you have a more urgent need for server-side streaming support, you could also check out Protocall (https://protocall.dev - disclaimer, I'm the author) - it supports all four rpc types (Unary as well as Client/Server/Bidirectional streaming), along with the structured input field rendering and automatic import resolution (via Github repo import).
I wrote it because existing tooling like BloomRPC and gRPCurl were difficult to use for anything more complicated than "Hello, World". I was also looking for tools that would let me send protobuf-encoded requests via HTTP/1.1 rather than gRPC, which didn't seem to exist at the time.