Has your wordpress website a mobile application? Do you want to push notifications from wordpress website to your application? Pusher plugin can achieve this job if you use Firebase Cloud Messaging in your application. If you make the settings in the mobile application correctly, the plugin will push a notification in every new post.
You can find all Firebase Cloud Messaging related information at this address.
How to push notification to mobile app
You can send a notification to all users who have subscribed to the topic you set from within your application.