I don’t follow it very closely, but as far as I know, they are the only one implementing the open protocol they designed (which doesn’t interoperate with ActivityPub). But there seems to be some efforts on creating a bridge: www.docs.bsky.app/blog/feature-bridgyfed

As you said, there are some recognizable faces and that may impact the adoption. But not being compatible with ActivityPub is a real bummer.