Cross-Platform E-commerce App Development

I'm looking to develop an e-commerce app for both iOS and Android platforms. The app will primarily sell physical goods.

Essential features include:
- User accounts
- Shopping cart
- Payment gateway integration

Ideal skills and experience:
- Proven experience in developing cross-platform mobile apps
- Strong knowledge of integrating payment gateways
- Experience with user account management and shopping cart functionalities
- Familiarity with e-commerce app design and user experience principles

Please provide samples of similar work done.