> So would it be possible to build a native emacs for android?

I checked this a while ago and unfortunately emacs comes with a relatively large pack of dependencies. Android on the other side does not deliver many standard libraries. Xorg libc and afaik dbus are a few dependencies which are not (natively) available on Android.
I tried Emacs in a debian chroot on my keyboard less device. It wasn't really usable and I doubt that keyboard based smartphones are much better since they most likely miss alt ctrl and other important keys.

Ideally we have something like Mobileorg and a emacs dameon running. Mobileorg could send emacs elisp code to execute and access all org-mode functions natively. This would allow to "reduce" mobileorgs task to touchfriendly input and result representation.

If I manage to port a very basic version of emacs to android I will let you know.

Greetings
Totti