Munki has a pkginfo key for the installer type "nopkg". In a self-hosted Munki environment, this allows pkginfo files to be added to a repository that do not have an associated .pkg or .dmg file. You can read the Munki Project docs on the feature here: https://github.com/munki/munki/wiki/nopkgs

This has a variety of uses, because it allows Munki to be used as a general script execution tool. An admin can use any of Munki's installation conditions (package receipt, installs array, installcheck_script, or OnDemand) to then run a pre or postinstall script embedded in the pkginfo.

One example of how this is used is the venerable PrinterGenerator tool, which generates nopkg-style pkginfo files to enable printers to be installed and uninstalled via Managed Software Center.

https://github.com/kevinmcox/PrinterGenerator

Combined with Custom Attributes, nopkg support has the potential to greatly expand on the script execution capabilities offered to a SimpleMDM admin well beyond the current Scripts/Jobs feature.