There may be other ways, but I usually grab the top track name box bottom edge, with Alt key down, drag it up or down. This re-sizes all tracks. I assume this is what you mean by vertical zooming.
Well in Cubase do the following and maybe will work for Nuendo as well?:
File / key commands (top left)
In Commands list, scroll down to Zoom in vertically
Press the key combination you would like to use (I used option + Z)
Click on assign…bingo! And when you zoom in, you will also see the note name.
But unfortunately, this does not work in the IN PLACE MIDI track editor on the arrange page…shame - actually it would be very useful when aligning MIDI notes to live played audio tracks, eg. adding a MIDI snare to a real one to make it really blast!