Develop a fonctionality for a mobile app

Hello, We are currently developping a mobile app using Good Barber. We are looking for someone to add a fonctionnality to our app. From the Home menu of the app, a user should be able to send notification to all users around him (Using geolocalisation and a radius of 300m around him) by pushing a button. All users will get a default notification with a pre-defined message. To add security and avoid abuse, a user can send 1 notification every 8 hours.