Official Munki documentation about custom conditions : https://github.com/munki/munki/wiki/Conditional-Items#admin-provided-conditions
You have to put theses files (not folders !) in /usr/local/munki/conditions (create the conditions folder if is not there) on the Munki client.
After a standard Munki check, you can look for the 'Conditions' dictionary in /Library/Managed Installs/ManagedInstallReport.plist
You can add this code in the site_default manifest to deploy a special manifest for a specific WS1 UEM group only.
<key>conditional_items</key>
<array>
<dict>
<key>condition</key>
<string>ws1_devicesmartgroup CONTAINS "Some WS1 UEM group name"</string>
<key>included_manifests</key>
<array>
<string>some special manifest</string>
</array>
</dict>
</array>
You can add this code in any manifest to deploy two special packages only on client where "anyfile" exist.
<key>conditional_items</key>
<array>
<dict>
<key>condition</key>
<string>anyfile == 'true'</string>
<key>managed_installs</key>
<array>
<string>special install 1</string>
<string>special install 2</string>
</array>
</dict>
</array>