I think it’s really imperative to be able to create subnotebooks in all platforms, or at least edit the notebook hierarchy (moving notebooks into others, or out of them).
I don’t know the current state of this discussion, but as far as I’m aware, this is only implemented in the desktop version. There’s currently a pull-request for that feature on the mobile app (not very active), but as for the terminal app it seems there’s no discussion whatsoever about implementing the feature.
I’d really like to start using this app, but this seems a bit troublesome.
[EDIT]. I could implement this myself for the terminal app if there’s some minimal guidance.