Cross-Platform Loyalty App Development

I'm looking for an experienced app developer to create a loyalty app for both iOS and Android platforms.

Essential Features:
- Point System: Users earn points on purchases.
- Rewards Catalog: Users can redeem points for rewards.
- Referral Program: Incentivize users to refer friends.

User Sign-up: Must be via phone number and OTP.

Ideal Skills:
- Proficiency in cross-platform app development.
- Experience with secure OTP integration.
- Strong UI/UX design skills.
- Familiarity with loyalty programs and gamification.

Please share relevant experience and portfolio.