Generally, Munki has no problems extracting icons from .app or .pkg items it imports. Adobe makes its installers a bit annoying to get icons out of, so when you import an Adobe CC item into Munki and try to get the icon out, you'll get this instead:
Attempting to extract and upload icon...
Can't generate icons from installer_type: AdobeCCPInstaller.
With some idea help from some people on the MacAdmins Slack team, I cobbled together a script that extracts the Adobe CC icons. The only bummer is that you have to actually install the Creative Cloud items on to a client machine first and then run the script on the client machine to get the icons.