Improvement for notification, alert sound, and location update to an iOS app. -- 2

Hi, I have an iOS app for food delivery service that needs improvement in its background service. It currently receives google firebase notifications that trigger an alert sound. The location update is done by polling an API from the backend. It is not working reliably now. I am looking forward to a developer who can improve this.
Feel free to ask any questions and I am looking forward to working with you.

This is a repost from the previous one. I have to use a fixed rate instead of an hourly rate to suit the financial department's requirements.