Kotlin Native E-Commerce Android App

I need a clean, fully native Android application written in Kotlin that lets shoppers browse products, add items to a cart, and complete checkout within the app. The flow starts with a simple Email/Password sign-up or sign-in screen; once authenticated, users can move seamlessly through product listings, detailed product pages, a persistent shopping cart, and a secure payment gateway.

Because this is core e-commerce, performance, crash-free stability, and responsive UI on Android 8.0+ matter more to me than flashy extras. Jetpack components (Navigation, ViewModel, LiveData) are welcome as long as the codebase stays modular and easy to maintain. Stripe or PayPal SDK integration is preferred for payments, but I am open to other PCI-compliant gateways if you can justify the choice.

Deliverables
• Kotlin source code structured by feature modules
• User authentication via email/password (Firebase Auth or a similar secure service)
• Product catalog screens pulling sample JSON or a lightweight backend API
• Add-to-cart, update quantity, and delete actions with local persistence
• End-to-end payment flow in sandbox mode, returning a confirmed order screen
• Brief README covering build steps, SDK versions, and how to swap in a real backend

I will review the APK on a physical device and inspect the repository; acceptance hinges on smooth navigation, successful test transactions, and clean, well-commented code.