It is possible to perform number of tasks using Microsoft Defender's interface in the PowerShell for example Get-MpComputerStatus , Get-MpPreference , Get-MpThreatDetection ,... and you may see the list on:
As for the Microsoft Defender ATP, you may start with:
Windows Security Center - WMI/PowerShell
I am looking for ways to interrogate Windows Security Center using PowerShell across my estate. Independent of the AV product/OS version in use. Essentially I want to show what Security Center GUI shows in PowerShell.
The key info I need is:
Overall health state / any current/recent alerts
Compare the engine/AV definition to the latest available and flag if not the most recent
Show the most recent available whether the installed one is the latest or not
Show the last quick/full scan date and results
There will probably be more needed in the future but that's a good starting point.