Envoy has to run to proxy grpc-web requests to the grpc server.
envoy -c envoy_dev.yaml # or use the docker-compose file
Add the following line to /etc/hosts (optional):
127.0.0.1 test.mydomain.com
Then run the frontend:
flutter run --web-port 40001 --web-hostname test.mydomain.com -d chrome
flutter pub run build_runner build