For the two people in the world who were wondering this, GNU Emacs runs just fine under Debian on a Raspberry Pi. It doesn’t leave much memory available for other stuff so don’t expect to do a lot at the same time as you’re running emacs. But it works!
sudo apt-get install emacs
At least 3. Possibly a few more.
Emacs user number 4 here. I did the apt-get as described. It appeared to work. All the normal stuff was printed. However, I can’t invoke emacs. I type ‘emacs’ and it says the command is unknown. I found the stuff in /usr/share/emacs/ however, there is no /usr/bin/emacs. What gives?