Cross-Platform Fitness App Build

I need a developer who can take my concept for a fitness and health application and turn it into polished, production-ready apps for both iOS and Android. The core experience revolves around helping users stay on track with their wellness goals through three essential functions:

• Workout tracker – users can log routines, sets, reps, time, and receive in-session guidance.
• Nutrition planner – meal logging, macro targets, and simple recipe suggestions tied to daily goals.
• Progress monitoring – intuitive charts, streak indicators, and milestone badges that visualise results over time.

I already have wireframes of the main screens and a clear user flow; what I need is the full mobile build, including intuitive UI/UX, secure user authentication, and a lightweight cloud back-end (Firebase or a similar service is fine).

Deliverables I expect:
1. Complete, well-commented source code for both platforms.
2. TestFlight and Google Play internal-test builds for review.
3. A brief hand-off document covering project structure, environment setup, and how to publish future updates.

If you have experience with cross-platform frameworks such as Flutter or React Native and a track record of shipping apps that integrate fitness sensors or health data, I’d love to see your work. Please outline your proposed tech stack, estimated timeline, and any questions you have so we can start right away.