@careyh I installed NP++ just now, default options. I went to a random *.exe file. I right clicked, this is what I see:
I can go to any file, anywhere, with any extension, and that context menu option shows up. Sublime and VS.Code have the same thing and it will show up in the same section of the context menu, such that if I had all three installed, I would see all three editors in my context menu, unless I explicitly disable them.
So yes, it binds to everything regardless of extension. I'll find the registry key(s) it creates in regedit and post that in a minute.