Hi,
I have read your requirement carefully.
I am a senior Android and iOS app developer.
And I am very familiar with backend and JSON.
1. Android-Java, iOS-Swift
2. Very familiar to integrate third party, FB, Google, Twitter, Payment method, etc.
3. Experience to get and put data with server. Testing via Postman.
4. Rich experience to use Google Map API
5. Design, is based on material.io.
6. The price would be confirmed after discuss. To be comfortable with you and me.
Hope to kindly reply,
From Peng