Hey Mr. abramin,
I have read that you need a mobile app developer, I am happy to tell you that I am really the right person for this job and I also work as a team leader.
I can develop any kind of application for you, I have many applications on offer, I hope you will take a look at them.
I have also worked in video calling and voice calling apps, you can hire me without any worries to start the business.
Here are my experience
✅Creating Material UI.
✅API integration.
✅GPS Tracker.
✅User notification.
I eagerly wait for you to start work, Bye.