I must admit that Nano's keybinding capabilities are pretty limited compared to, for example, Atom's. For instance, you cannot use arrow, Tab, Esc keys or even Super or Shift as a modifier. Given the range of keys you can use, I honestly don't understand why they don't allow to use the mentioned keys. Probably their rc-parser is too straightforward and primitive.

Also, I wonder why they don't allow to define own keyboard macros for external commands on the buffer at any time, not just insertion.

But nevertheless, you still have just a decent text editor (with syntax highlighting) in the first place, not an OS inside an OS (like in Emacs or Atom), and not archaic controls for arrowless keyboards and useless rot13 plugins (like in Vim).

Here's your starting point: http://www.nano-editor.org/dist/v2.4/nanorc.5.html