Retail Store Cross-Platform Mobile Application

I need a cross-platform mobile application for a retail store with a subscription-based loyalty card system. The loyalty card should only be available to users who have an active eligible subscription. Users should be able to sign in using Apple, Google, or a 4-digit verification code sent to their email. After signing in, the user should see their personal loyalty card, including information such as how much they have spent with the card, how much they have saved, their current subscription plan, and the benefits included with that plan. At checkout, the customer will scan their personal loyalty card to receive the discounts and benefits connected to their subscription. The app should also include store locations, purchase history, total spending, total savings, subscription level, and available benefits. In the future, the application will need to integrate with the B-MARKET POS system so that purchases, discounts, spending, savings, and customer information are synchronized automatically. There is currently no finished UI/UX design for the application or the loyalty cards, so the developer will also be responsible for creating the app design. Payment functionality must also be integrated into the application so users can purchase and manage their subscriptions.