WordPress being able to post via ActivityPub to Mastodon would be a big deal. And I'm happy to see Automattic get involved in this space. They're in the hosting business, so their incentives are much more aligned with the Fediverse than Meta, which is just centralized surveillance capitalism. Plus, Automattic is run by people who understand and support open source software and Meta is run by greedy, stupid assholes.
(Disclosure: I worked at WordPress on Reader.)