C#, Xamarin Forms, Xamarin Essentials, Firebase, Firestore, GoogleMaps, ReactiveUI.
Make a changa or hire people and get quick, few-hour jobs in your city. Such as mowing lawns, washing cars, walking dogs, etc. You publish the job, with its price and hours. And people offer themselves, so that later you can choose who is going to do it.
https://play.google.com/store/apps/details?id=com.civeloo.changa