This works by going via https://fed.brid.gy/ which goes takes the fediverse bridged version of your Nostr account from mostr.pub and then creates a parallel account on Bluesky for you. Anything you post on Nostr will show up on Bluesky. I’m not sure if all the replies go back or just the folks who’ve opted in to bridging from Bluesky back to the fediverse.

And if you want to bridge to Twitter you can do that too at connect.nos.social