Google Sheets Integration Mobile App Development

I'm seeking a skilled mobile app developer to create an application that integrates with Google Sheets.

The app's primary function will be data entry, and users will be able to both add new entries and edit existing ones on the Google Sheets data.

Key Requirements:
- Mobile app development expertise, particularly with Google Sheets integration.
- Proficiency in both iOS and Android platforms.
- Clean, user-friendly interface design.
- Secure data handling and user authentication.

Ideal Skills and Experience:
- Proven track record in mobile app development.
- Experience with Google Sheets API.
- Strong UI/UX design skills.
- Detailed project proposals are required for application.