It works really well. If you have the URL of either a user or community, you can follow it from a Fediverse platform like Mastodon or Pleroma.

Example: follow @realcaseyrollins@narwhal.city to follow this account via Mastodon or Pleroma. To follow the Bookmarks community on Mastodon or Pleroma, follow @bookmarks@narwhal.city.

Now, federated posts act weird on Pleroma/Mastodon. The title shows up as a CW, and your post will only have a text body if you write a description, so link posts don't completely work via federation yet. Also, I don't think we can follow Mastodon/Pleroma accounts from here.