Nice project. But at what point does Markdown just become Emacs Org-Mode? At least with Emacs you can write Lisp to make your document do anything you want.
I'm struggling to figure out why I wouldn't just use Emacs Org or even Typst for this use case.
Deepening on who your users are you might also say "at least with markdown they write Lisp and make their documents do whatever they like."