I have heard rumours that one can get Emacs up and running fairly well in Termux, but I haven't explored it personally yet. Orgzly is good enough for most of my Android Org needs.
For typing, Termux's "extra keys row" makes ctrl and meta combinations possible with your favorite keyboard: https://wiki.termux.com/wiki/Touch_Keyboard
...or you can just use Hacker's Keyboard (but I find it too cramped).
Git also runs fine under termux if that's what you use to sync your org file.