Facebook Private Reply :)

Hey Fam :v:️ Has anyone seen the automated Facebook Private Reply bots? Like https://www.msghero.com

I’d like to create my own version for internal use, but just wondered if any of you could point me in the right direction. I’m well aware of the Graph Api, and have gotten a Private Reply option working, but it’s the automation part I’m not so sure on:

Is there a way to get live notifications of new comments in a post?
Or do I need to routinely check a post for new comments?