Enhancing Expo React Native Mobile App UI + Features

I'm looking for a skilled mobile developer who can help improve the user interface of my language learning Expo mobile app and fix some bugs. The developer will also be tasked with integrating new features into the app.

We have the core part of the app complete, we now need additional features to be added:
- Push notification reminders to enter the app
- Onboarding flow + payment screen
- Daily streaks
- Gamification with points for completing lessons in the app
- Global leaderboard / daily / weekly/monthly
- Save words to a 'Word bank'
- Word of the day.

Ideal candidate should have experience with:
- Mobile app development, React Native specifically with Expo
- User Interface design and improvement
- Troubleshooting and debugging