Integrate Android App with Firebase & Expo

I'm looking for a professional who can integrate my Android app code with my Firebase backend. The app needs to utilize Firebase's Authentication and Firestore Database services. The integration should be done in a way that allows me to run the app on Expo using Visual Studio.

Ideal skills for this project include:
- Extensive knowledge of Firebase services, especially Authentication and Firestore Database.
- Proficient in Android app development.
- Experience with Expo and Visual Studio.
- Strong background in integrating app code with backend services.

Please note, my Firebase is already set up, so I just need assistance with the integration. Your expertise can help me get this done efficiently. Looking forward to your proposals.