Cross-Platform Mobile App Development

I'm seeking a seasoned full stack developer to create a comprehensive mobile app.

Key Requirements:
- Development for both iOS and Android platforms.
- Implementation of essential features including:
- User authentication
- Push notifications
- In-app purchases

Ideal Skills:
- Proficiency in full stack development with a strong focus on mobile apps.
- Previous experience with user authentication systems, push notification integration and in-app purchase setup.
- Familiarity with both iOS and Android development environments.

Please provide examples of similar projects you have worked on in the past.