I think this might be a limitation of the Zettelkasten note. What you could do (and is better in my opinion because it also learns you how to get comfortable with split panes) is to open a split pane and the add a new Zettelkasten note.
My workflow for this (using remapped shortcuts) is CMD+D → Split Vertically and CMD+N → Create new Zettelkasten note
You could also create a feature request for the Zettelkast prefixes like “Add option to create a new Zettelkast note in new pane”