A bunch of interesting observations from Sven-S. Porst:
PIDs in X.5 don’t restart from 0 again once they reached the 215 region. Rather, PIDs go on and on and on.
And thus Apple had to use the less-than-ideal technique of using a small custom icon graphic as a custom icon for the huge folder icon.
And thus, with a few clicks in the Keyboard preferences, I had the Finder set up to invoke ‘Show Package Contents’ for a Command-Option-Shift-O.