Custom Mobile App Feature Development -- 3

Seeking an Experienced Flutter/Native Developer — Android & iOS

I need a seasoned developer who's comfortable shipping the same experience on both Android and iOS. The core tasks for this phase are:

Local scheduled and repeating notifications that fire reliably on both operating systems, including edge cases like app-kill and battery optimization on Android OEMs (Xiaomi, Oppo, Vivo, etc.)
Speech-to-text for two distinct use cases: quick voice-note capture and real-time voice commands
Text-to-speech, with a choice between standard system voices and richer AI-generated voices
Full Firebase integration — email/social auth plus push notifications
Razorpay payment integration, covering both one-time purchases and renewable subscriptions
Thorough testing and debugging on real hardware (not just simulators/emulators) before submission to the app stores

Process: I'll sign an NDA and a straightforward IP assignment agreement before sharing the complete product spec.

What I need from you to get started:

2–3 live apps or repos demonstrating similar work — ideally showing notification reliability, payment flows, or voice features in production
Your preferred toolchain (Flutter, React Native, native Kotlin/Swift, or other) and reasoning for this project
A rough sense of your CI/CD setup and how you'd approach timeline planning from day one