Emacs should run fine on PostmarketOS [1] [2]. Thus Org, too.
Emacs runs perfectly fine on Android via termux and org works as well (as does gnus!).
But the issue is the keyboard.
Have you tried "Hacker Keyboard"? I don't
use my phone for much, so I can't really say, but I know it has
esc and ctrl keys and other "real" keyboard features.