Looks like it is available for free, but you get a really awkward username. I just enabled it on an old WP.com blog that I have on a free account and while @kelson.wordpress.com@kelson.wordpress.com works (I was able to subscribe to it from both Mastodon and GoToSocial), it’s a bit unwieldy.
Not sure how you get from Fediverse people researching what server admin/moderation structures work well and which ones don’t to CIA censorship.