Cross-Platform Mobile App Build

I need a fully functional mobile application released on both Android and iOS stores. Although the exact vertical is still being finalised, a few must-have features are already clear:

• Secure user authentication (email, social, or phone-based—whichever you recommend)
• Real-time push notifications delivered reliably on both platforms
• Seamless integration with a third-party analytics tool so I can track events, funnels, and retention from day one

You will handle everything from setting up the codebase and configuring the analytics SDK to preparing production-ready builds for Google Play and the App Store. Clean, well-commented code and brief hand-off documentation are required so my internal team can maintain the project afterward.

If you have previous experience shipping cross-platform apps with these exact capabilities, I would love to see a short example or two.