The OneSignal is the popular WordPress push notifications plugin. You can send automatic notifications to the readers whenever new content is published. The plugin allows you to set opt-in for the site visitors to configure desktop notifications.
The Push Notifications for WordPress (Lite) plugin has a built-in hub that allows WordPress to send push notifications directly. You can send real-time alert messages to the website visitors. This WordPress push notifications plugin is great for personal blogs or for beginners.