There’s currently no way to assign a keyboard shortcut to open the Drum Machine instrument window in Cubase. To open it you have to double-click the instrument slot in the track, which interrupts workflow.
It would be very useful to have a key command that opens the Drum Machine window for the selected track, similar to how other instrument windows can be opened via keyboard shortcuts.
Ideally this would appear in the Key Commands window so users can assign their own shortcut.