React Native WooCommerce POS App - Android

Hello, I have the following app, its React Native WooCommerce POS App
https://codecanyon.net/item/rpos-react-native-woocommerce-pos-app/31290453

I need the following:
- Edit the app to support WCFM multivendor for WooCommerce
- Every single vendor can use the app for his market place
- Edit the app to receive orders from customers via API
- Edit products in WooCommerce and add new things like batch number and expiry date.
- The app must working in 7 or 8 inch tablets without problems

I need to know the cost and timeframe

Thank you