Getting gRPC Metadata in NestJS from Client

Question

I would like to be able to read gRPC metadata when making a unary call with the gRPC client. Currently this is already possible with StreamCalls' which is also properly documented, but I can't figure it out with Unary Call's

Consider the following code:

Simplified Provider:

{
    provide: 'SERVICE_GRPC',
    useFactory: () => {
        return ClientProxyFactory.create({
            transport: Transport.GRPC,
            options: {
                package: 'myPackage',
                protoPath: 'my.proto
                url: '127.0.0.1',
            },
        });
    }
},

Simplified Class

interface SomeService {
  someGrpcMethod: (argument: Request) => Observable<Response>;
}

class SomeClass {
  constructor(@Inject('SERVICE_GRPC') private readonly _client: ClientGrpc) {}
  
  onModuleInit(): void {
    this._someService = this._client.getService<SomeService>('SomeService');
  }
  
  someMethod(): void {
    const observer = this._someService.someGrpcMethod({param1:true})
    // Need the metadata send by server here
    observer.subscribe(...);
  }
}

Does anyone know how to do this?