Absolutely, the shortcut help is so useful!

I believe that Nano and Pico copied it from Wordstar.

That seems very likely. One of the first things I'd noticed back in the early 90s when I got my shell account and used Pico for the first time was that the UI was similar (not exact copy, mind you) of how Wordstar was, with some basic guidance at the bottom to get you started.

Also kind of reminds me of the old Telix terminal software for MS-DOS, with the bottom status bar. Not exactly the same, but again quite similar in the approach to have you just quick glance at the bottom of your screen for a HUD.