> A simple derived exporter? Or (on the LaTeX side) the comment package?
>

Thank you. I managed to achieve this with the following code:

(defun my/latex-remove-NOTES-blocks (text backend info)
  "Filter special blocks from latex export."
  (when (eq backend 'latex) 
    (if (string/starts-with text "\\begin{NOTES}") "")))

(eval-after-load 'ox '(add-to-list
                       'org-export-filter-special-block-functions
                       'my/latex-remove-NOTES-blocks))


This was the first emacs-lisp code that I wrote with knowing what I was doing. :)

Best,
Joon