In SEDE (specifically, in the Posts table), is it possible to get the markdown for a post, i.e. what you would see if you went to the site itself and tried to edit it? Querying for Posts.Body only gets you the baked HTML.
While it's arguably easier to use the API with a filter that includes body_markdown, you can grab the latest PostHistory entry with PostHistoryTypeId 2, 5, or 8 and use the Text field, which contains the Markdown of the post body. You can see this in action in this example query.