Build Cross Platform Mobile App

I need a complete mobile application that runs smoothly on both iOS and Android. While the final concept is still open, I know I want a professionally coded app that is ready for the App Store and Google Play, with thoughtful UI/UX and clean, maintainable source code included.

Here is what I’m looking for from you:
• Help me refine the app idea into a workable feature set, then design an intuitive interface around it.
• Develop the full codebase in a modern cross-platform framework (React Native, Flutter, or a comparable alternative you can justify).
• Integrate any essential backend services, APIs, or cloud functions required for real-time data and user management.
• Test thoroughly on a range of iOS and Android devices, resolve bugs, and guide me through publishing in both stores.

Hand-off must include the complete project files, build instructions, and a brief walkthrough so I can maintain or extend the app later.

If you have a portfolio of live cross-platform apps and can collaborate on product direction as well as development, I’d like to hear how you would approach this project and an estimated timeline to launch.