How to send a push notification if subscribed to a specific content with a unique title?

Question

Text Processing Automation

Good day! I will try to formulate the question: the user subscribes to news on the site with a specific name (strict compliance), for example, "Once upon a time there was a dog" or by tags of materials and clicks on a button like "Notify about appearance". When an article is published (if the title matches the text specified by the user), a push notification is sent to the browser or in applications (either by mail or other channels: instant messengers and others) that this content has appeared on the site and he can read it.
Do such scenarios exist in practice? Thank you for your attention.