Productivity App for iOS & Android

I want to turn a clear productivity concept into a polished mobile application that runs natively on both iOS and Android. My goal is to give users an intuitive tool that helps them organise their day, track progress and stay focused—nothing bloated, just clean, fast and reliable... (Budget: $250 - $750 USD, Jobs: Android, Backend Development, Flutter, iOS Development, iPhone, Mobile App Development, Mobile App Testing, React Native, UI / User Interface)