If you head to Settings > Glyph Interface > Notifications, you should see the option to “+ Add new Essential”.
From here you can set it to almost any app, some of which will allow you to be a bit more specific with the notification. For example if you select whatsapp, you’ll be able to set the essential notification to specific chats.
Once set pop your phone face down to fully utilise the feature and you’ll notice that the top right diagonal glyph will remain lit for the app that you’ve set once you get a notification.