Follow the following instructions to import the latest macOS upgrade to munki for distribution to all Orchard Macs.
To download the latest macOS release we use a python script by Greg Neagle. This script can create disk images containing macOS Installer applications available via Apple's softwareupdate catalogs. The script is already located in a cloned github repo located on the build host Autumn-Glory /srv/munki/macadmin-scripts please ensure the repo is up to date prior to running.
Run the script installinstallmacos.py as the root user, chose a macOS and download.
Once you have your dmg downloaded, use munkiimport to manually add the dmg. The name should always relate to the macOS for example Install_macOS_Big_Sur and ensure the version is correctly applied, Installer_item_location is macOS.
Find the product page icon icns from within the dmg, you may have to mount the original dmg and search. Create a 256x256 png file of the icon, named the same as the munki pkginfo's Name key to /srv/munki/orchard_repo/icons
Use manana.orchard.private to create a new computer attribute mapping. Insert an attribute value of a pre-configured Jamf Smart Group all the computers you want to scope to.
Greg Neagles script - https://github.com/munki/macadmin-scripts
Using Munkiimport https://github.com/munki/munki/wiki/munkiimport
Jamf smart group example https://jss.orchard.ox.ac.uk/smartComputerGroups.html?id=748&o=r