Setup fyne dev environment: (assumes familiarity with fyne.io)
https://developer.fyne.io/started/

server app (run from Desktop)
run ./serverApp/main.go from a separate terminal

fyne client app (run from Desktop)
run ./main.go from another terminal

Original gRPC code with added int32 response message or reply
https://github.com/grpc/grpc-go/tree/master/examples/helloworld

Repo is self-contained
both client and server app uses local module|folder ./helloworldProto

Android build (from Windows machine), create .apk file:
download NDK https://github.com/android/ndk/wiki

 set ANDROID_NDK_HOME=c:\somefolder\ndk\...

Install fyne command

go install fyne.io/fyne/v2/cmd/fyne@latest

To test the Android fyne client app with a cloud server

update localhost with IPv4 from grpcClient.go before building

cd to project folder, then build apk file using fyne command

cd fyne_gRPC 
fyne package -os android -appID com.fynetest.fyne_gRPC

fyne_gRPC.apk is created, about 127MB file size