Apple is bringing changes to Software Update via MDM this year.
Made mandatory with macOS 11 Big Sur, Software Update for macOS gains some parity with iOS and there is now finer control of iOS version for devices.
macOS 12 devices now report the right information to properly use the Apple Software Update Lookup Service. Specifically, the ProductVersion key is now supported for macOS (allows definition of update version to install) and FileWave will be sending 2 InstallSoftware commands as per Apple's direction in order to make software updates happen in a more timely fashion.
Starting with iOS 15, it will be possible to stay on the previous version (today, iOS 14) and still get minor updates. A new Settings command allows to define if the end-user will be presented the most recent update (iOS 15), the oldest (iOS 14.x), or both options as seen below in the updated Command Policy profile.