I am able to get all the page posts that can be promoted via the endpoint given at https://developers.facebook.com/docs/marketing-api/campaigns/objectives#connection_objects
eg query:
https://graph.facebook.com/v2.5/[PAGE-ID]/promotable_posts?fields=id&is_published=true&access_token=[TOKEN]
but how do I get all the posts that are already promoted? I am unable to find anything on the FB API docs.