I make substantial use of prettify-symbols
in my programming buffers. A snippet of some of my python symbols:
(add-hook 'python-mode-hook
(lambda ()
(mapc (lambda (pair) (push pair prettify-symbols-alist))
'(("for" . ?∀)
("in" . ?∊)
("not in" . ?∉)
("return" . ?⟼)))))
This works fine for all cases except (html) exporting.
Pretty symbols from source code, or even directly from org-mode text, will not transfer over after exporting.