I remember about 10-15 years ago there used be packages aimed at supporting ActivityPub, or whatever it was called back them. One of them, for Ruby, was even maintained by Steve Klabnik of Rust fame.
Perhaps there's something like that now again, but last I checked, the protocol got quite a bit more complex in its requirements, so there was no ready-to-go option, everything required a lot of manual testing and adaptation.
There are a whole bunch of small projects that turn an RSS feed into ActivityPub posts. In theory, a well-placed JSON file (the webfinger part) could direct anyone trying to subscribe to the blog to a dedicated fediverse server.
The protocol has been wrapped a whole bunch of times in various languages, but I don't know what protocol this particular blog uses, so I can't comment on what would be appropriate.
A similar level of cross-platform library support for ActivityPub would greatly ease its adoption across the universe of Internet applications.