Schedulable script that updates a WMI variable - see https://github.com/N-able/ScriptsAndAutomationPolicies/blob/master/AV%20Status/AVStatus.vbs for and example of that being done. I am guessing new/custom variables can be created as well.

Then a custom service can be created in N-central that can monitor the value as per - https://secure.n-able.com/runbook/content/monitoring/rb-wmi-based.htm