In the past, it was almost-always possible to get offline installers for Apple macOS updates from https://support.apple.com/downloads/ (you get a PKG file in a DMG file).
However the same doesn't seem to be true for Catalina. So far none of the updates have been made available.
- Supplemental Update 19A602
- Revised Supplemental Update 19A603
At-least not in the usual place, they can only be installed using the built-in software updater.
Are these being made available for download somewhere, or is there any more information available on this issue?