Instead of a line for each app/function, use the horizontal space!
Something speedy which the user can customize the buttons and command.
Similar "rows of buttons" exist in other systems, even Office AND I remember a shell extension on Windows that had media control buttons to preview audio files from the context menu. That was a long time ago.
You can see many shellex efforts out there, for example here and this old tool by Michal Mutl (mitec.cz):
Does anyone have the chops for it?
Attachments of the above images, ignore: