I keep hearing good things about Visual Studio Code and I see people using it here at work, in a trendy Dark Mode. (Of course, 3270 had Dark Mode from the beginning. Me working on z/VM next to them, on MacOS night mode, makes for a consistent appearance).
It would be great if someone could look into that! I am too busy at the moment, but I will do a quick check on it, to see which formats it accepts. Maybe we can have a look at the support for nano and see what can be done. (Like, if someone had done a formatter for TextMate, we now would be very close to Atom and Sublime and Brackets support because those all look alike qua syntax colourers).