Firebase Expert for React Native Safety App

I need an experienced Firebase backend developer to assist with an existing React Native/Expo mobile safety application.

The Firebase project and GitHub repository have already been created. The developer will work with my existing development team to review and implement:

• Firebase Authentication and token validation
• Firestore database architecture and collections
• Firestore and Storage security rules
• Cloud Functions using Node.js/TypeScript
• Firebase App Check
• Integration support for the React Native/Expo application
• Testing, debugging, and technical documentation

The application includes trip information, emergency contacts, safety check-ins, location-related features, alerts, and SOS functionality. Strong Firebase security experience is required.

The developer must:

• Have proven Firebase and React Native/Expo experience
• Work through our GitHub repository using branches and pull requests
• Collaborate with our team through Slack and video meetings
• Provide written progress updates
• Document all work and provide a recorded handoff
• Never make production changes without approval

Please provide examples of relevant Firebase projects and explain your experience with Firestore security rules, Cloud Functions, App Check, and React Native/Expo integration.

I want to begin with a small paid architecture and security review. Additional implementation work will be divided into fixed-price milestones after the review.