[tekknolagi]

It would be nice if it overrode EDITOR with some command that opened a new pane in your existing Nvim session. That seems doable.

Alternatively, Tim Pope's fugitive is pretty great and you can write :Git commit and it does just that.

[scottlamb]

It could even overlay the terminal pane for the duration of the command with the buffer pane. So it'd look a lot like opening the second editor instance, except incorporated with the first editor's buffer list, registers, etc.