Push notifications and in-app messaging are typically handled using a messaging service that is integrated into the UberEats Clone App. This service can be used to send push notifications to users when their order status changes, such as when their food has been prepared or when their delivery driver is on the way. In-app messaging can be used for communication between the customer and the restaurant or delivery driver. The messaging service is usually based on real-time communication, allowing for instant updates and notifications to be sent to users. This can be implemented using technologies like Firebase Cloud Messaging (FCM) or WebSockets. The messaging service can also be integrated with the app's backend, allowing for more advanced features such as automated messages and personalized notifications.