Hi,dear
I can develop your app properly.
I already implemented fetching contacts from phone contacts.
The app will send user selection from contacts to the web server and web server will determine if the contact is user of the app or not.
If he is user of the app , it will send the connection request directly by using push notification, so the user will receive the request immediately.
If the user gets the notification and allow it, they will share their location by using Google API.
The location data will be sent to the backend web server and it will be transferred each other.
That's it.
I have great logic to implement it and have strong skills to accomplish it, too.
I look forward to your response.
Regards.