yarn && \
yarn dev

Got to http://localhost:3000 and make sure each API call works. You might be required to login first.

Open the developer console and check the network tab. You should see the API calls and the responses.

cd packages/AmplifyJsCustomClientsPentestRN && \
yarn && npx pod-install && yarn [ios|android]

The iOS or Android emulator should open and you should see the app. Make sure each API call works. You might be required to login first. You can also open the developer console and check the network tab. You should see the API calls and the responses.