How to change the default macOS login window keyboard layout? I type using a keyboard layout other than the standard QWERTY. This question will apply to those who type using Dvorak, Colemak, QWERTZ, or any other international or non-standard keyboard layout.

My keyboard layout (Dvorak) is different than the standard keyboard layout for my country / locale. So this question isn't simply solved by setting a default locale; I also need to specify a default keyboard layout.

When I log in to my macOS user account, my personal keyboard layout is always used. It's also selected on the Lock Screen if I ever Lock the computer.

But when I first boot my Mac after a Restart or Shut Down, the QWERTY keyboard layout is always selected.

I'm forced to hunt-and-peck my password because my keyboard layout is not set. Or, I can manually change the keyboard layout via the Input menu (which is shown, but is not the focus of this question).

How can I change the default keyboard layout used on the macOS login window / startup screen?
In Terminal, run this to copy your keyboard settings to the default settings:
sudo cp ~/Library/Preferences/com.apple.HIToolbox.plist /Library/Preferences/
via Change the default keyboard of OSX login screen permanently