Well apt-get is for debian packages, SFOS uses RPM's which means you just need to use pkcon or zypper to work with it, otherwice the experience is pretty much identical.

I suppose there are lots of ways to get better console experience to android devices, however all those are more or less glued-on-top solutions; it is a pain to maintain your setup and you will miss lots of the advantages of the simple GNU/Linux userland.

There's loads and loads more to it. The whole android userland is a perversion of the real thing. It's a bad joke. You can patch it and add stuff to make working on a terminal better but why bother since the user experience will always be inferior.

On true GNU-userland-having mobile device like SFOS you can really easily do anything you can on a larger desktop machine, anything.

Porting just about anything is possible, of course some things are harder than others. I have not looked into emacs but I suppose if one version has been ported it is no-brainer to port a later version.