To do it manually will probably require 3 or more steps, the first of which is launching an app (Disk Utility, Terminal, or ?).
I just looked at Automator in the Applications folder, and it offers some possibilities to make that process shorter. An Applescript saved as an App might do the trick as well. I know very little about either, but someone here might help.
An Applescript would likely contain something like the following:
Run shell script "xxx"
That would give you the info in an open Terminal window. You could map that to an F key or put it in the Dock, giving you 1 step to get the info you want.
I don't know enough about any of these to give advice beyond what I have.
This might help:
Since you didn't say you wanted to get this info on a "random" Mac, I did not consider that.
Open Disk Utility and cycling thru the volumes to find the one that will not allow you to "Repair Disk". That will be the current boot drive. This method will also give you the hierarchy, which drives contain which partitions, and how many there are.