How can you find the icons for System Settings

[FireFingers21]

Inspired by @vitor's System Settings workflow, I'm playing around with additional shortcuts to the preference panes in System Settings. However, I've had no luck finding where macOS stores the icons for all of its preference panes. How were the icons sourced for this workflow? Is there a file or directory I'm missing, were they just obtained by screenshot, or something else?

[vitor]

I have explained the process in the thread.