I was going to ask if it’s only on the commercial wordpress offering but nope turns out they’ve put it out a plugin. https://github.com/Automattic/wordpress-activitypub

I wish this was a start towards a push for ActivityPub support across blogging platforms and feed readers.

In particular, it would be interesting if some form of support for statically-generated ActivityPub feeds was a thing among the software acting as consumers. That’s the one thing that still makes RSS/Atom be better of an option for many blogs that are built statically.