Copy a region of ORG-mode code to Markdown formatted and un-filled text.

copy-markdown.el

(defun r/copy-org-to-markdown (point mark)
  "Copy the region from POINT to MARK as Markdown."
  (interactive "r")

  ;; Load a trimmed copy of the highlighted region to memory
  (let ((astring (s-trim (buffer-substring-no-properties point mark))))
    (with-temp-buffer
      ;; Copy the highlighted region and run 'export to markdown' org command
      (insert astring)
      (setq org-export-with-toc nil) 
      (setq org-export-with-broken-links t)
      (org-md-export-as-markdown)

      ;; Correctly 'unfill' the copied region
      (markdown-mode)
      (set-fill-column 10000)
      (fill-region (point-min) (point-max))
      ;; (unfill-region (point-min) (point-max))

      ;; Copy to clipboard and remove window
      (clipboard-kill-region (point-min) (point-max))
      (message "Copied markdown to clipboard!")
      (delete-window))

    ;; Done work - jump to end point.
    (deactivate-mark)
    (goto-char mark)))

;; On Mac: Command-Shift-C copies org to markdown.
(define-key org-mode-map (kbd "s-C") 'r/copy-org-to-markdown)