Bluesky comes up in the latest ActivityPub newsletter update from Ghost:

Another cool thing that happened last week was that we enabled a bridge to BlueSky — an alternative decentralized social network which doesn’t use ActivityPub, but instead uses its own alternative protocol.

I was confused on my first reading of this. They’ve enabled Brid.gy, not built anything specific for Ghost. Also, I’m sorry this is so nitpicky, but no one in the fediverse seems to be able to spell Bluesky correctly.