Yep, I investigated both of those options. The first option, Zapier, isn’t free. You can make up to 5 free Zaps and those are single-step zaps. This is exactly what was said in that thread, so the alternative that was proposed was the discourse-chat-integration which is supposedly an official plugin. I think this is the closest way to do what I want to do.
The last option seems to be an RSS feed plugin:
Update: After learning to properly setup the rules and configuring the webhooks, the chat-integration does exactly what I wanted! Thanks.