Eventually an entire extension would be ideal, just like I could reply to tasks, I’d like to be able to reply (if the instance policy lets me do it) to instance block announcements, if possible directly, as a mod, from the social extension; I’d like as well to be able to share these instance blocks to different circles by boundary, as usual, and for example to let a large circle of instance roles follow my instance blocks, and a smaller circle of instance roles comment or interact with these instance blocks (otherwise than by clicking on the "block" button).

The main difference would be, I suppose, that these boundaries would be set by a specific role on behalf of the instance and that you wouldn’t manage the permissions user by user, but instance role by instance role, e.g. if you have moderators and new_followers_monitors on instance A and B, then you let all the moderators on instance A follow the instance blocks, but you’re free to assign different permissions to the moderators on instance B.