Horizontal scrolling in nano editor?

I'm pretty sure you cannot do that in nano. The closest you could get would be line wrapping, precisely "soft wrapping": Esc+$.

This will wrap lines so you could see them all on the screen.

_{Source: https://www.nano-editor.org/dist/v2.9/nano.html (search for --softwrap)}

You could get this kind of behaviour with vim, though, the editor is more configurable. See: https://ddrscott.github.io/blog/2016/sidescroll/