Pro tip: How to extract contents from 'Payload' file in a apple macOS update package?

How to extract contents from 'Payload' file in a apple macOS update package?

There is an undocumented option to pkgutil, --expand-full, which uses the same syntax as pkgutil --expand.

pkgutil --expand-full [pkg] [dir]

This will completely "unarchive" a pkg or mpkg file.