Google OAuth Integration in Android App

I'm looking to integrate Google OAuth into my Android app. The primary goal is to facilitate both user authentication and access to various Google API services.

Key Requirements:
- Implement Google OAuth for user authentication.
- Enable access to Google API services through the app.

Please note, the specific API services I want to access are not yet determined, so your solution should be adaptable and capable of interfacing with a range of Google services, including but not limited to Google Drive, Google Calendar, and Google Contacts.

I have an existing backend server that can handle OAuth tokens. Therefore, the chosen professional will not need to set up a new server or a serverless solution.

Ideal Skills:
- Proficient in Android app development.
- Experience with Google OAuth integration.
- Familiar with various Google API services.
- Capable of building adaptable and flexible solutions.

Looking forward to your bids.