In case of mc, ^O switches to same background shell, even from editor. So, variables, functions, and command history is same. Moreover, I can run command in shell and return to mc or mcedit to continue work when shell command still works (with limitation that current working dir will not follow selection in mc). It feels like real shell, not a subshell.
In `nnn` selection works seamlessly between multiple instances.
The shell in `nnn` is also a real shell with your complete env settings. So it remembers everything.
I can't think of a workflow where you are working both in the shell and the file manager when you have selection in place. It's a convenience, yes. But both are exclusive in nature.
