There's also https://github.com/uw-labs/bloomrpc/blob/master/README.md which is ...

dewey on May 28, 2019 | parent | context | favorite | on: Why We’re Switching to gRPC

There's also https://github.com/uw-labs/bloomrpc/blob/master/README.md which is kinda like Postman but for gRPC. I didn't see it mentioned in the Caveats section of the post so maybe useful to someone else too.