Cross-Platform Mobile App Development -- 2

I need an experienced mobile app developer or team to build a secure, cross-platform mobile application for Android and iOS using React Native.

Key Requirements:
- Cross-platform development (React Native)
- Secure user authentication (email/password, biometric)
- Integration of payment gateways (details to be discussed)
- Strong communication and clean code practices
- Willingness to sign an NDA

Please share your:
- Portfolio
- Tech stack preferences
- Availability