Remote EV Charger Management App

I need a production-ready mobile application that lets drivers start, pay for, and document charging sessions at our remote EV stations. The app must run smoothly on both iOS and Android and connect to the existing hardware through a simple QR code that is affixed to every charger.

Core features I must see in the first release:
• QR code scanning to identify the exact charging point
• Secure fee collection, with the amount calculated automatically from kWh and tariff tables
• One-tap activation of the charger and instant receipt issuance in PDF or email

For authentication I want phone-number sign-in using OTP verification; no email, social or biometric login is needed at this stage.

Clean, straightforward UX is critical, and the codebase should be structured so future additions—like dynamic pricing or loyalty rewards—can slot in without major refactoring. Whether you prefer native (Swift and Kotlin) or a robust cross-platform framework (Flutter or React Native) is up to you, as long as performance and hardware communication remain rock-solid. I will provide API documentation for charger control and billing, branding assets, and the required QR format.

Please outline your proposed tech stack, timeline to a testable build, and any past work with hardware-integrated mobile apps or payment gateways so I can gauge the fit quickly.