My recommendation for Automattic and Bluesky.
Automattic already fully supports RSS 2.0 in both directions, in all their products.
This gives us the most interop with the most respect for prior art. No need to reinvent. There’s nothing special about Bluesky, they can use what we’ve all been using for 20+ years.
It’s really very simple, let’s hook everything together and let the users and developers create.