I thought Pinning from Discourse might follow the same philosophy as a share to FaceBook, where it automagically formats what FB wants to see
So instead of FB requiring summary and image?) in this instance, by selecting Pin from the share options it would display what Pinterest wants to see i.e. only an image.
And instead of FB’s options for timelines to post to, it would list your boards to Pin to.
What I have just said comes with 100% admission that I have no technical clue what is involved in that process so if it can only be done on image only posts, I will work out how to make that work.