List GPO Client Side Extensions. Based on https://deploywindows.com/2016/02/11/windows-10-group-policy-client-side-extension-cse-list/.

Get-GPClientSideExtensions

function Get-GPClientSideExtensions {
    Get-ChildItem "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\GPExtensions" | foreach {
        $guid = ($_.Name).Split(“\”) | Select -Last 1
        $props = Get-ItemProperty $_.PSPath

        # Guessing CSE name in order (default), ProcessGroupPolicy, ProcessGroupPolicyEx
        if ($props.'(default)') {
            $description = $props.'(default)'
        } elseif ($props.ProcessGroupPolicy) {
            $description = $props.ProcessGroupPolicy
        } elseif ($props.ProcessGroupPolicyEx) {
            $description = $props.ProcessGroupPolicyEx
        } elseif ($gpeGuid = "{35378EAC-683F-11D2-A89A-00C04FBBCFA2}") {
            $description = "Administrative Templates"
        } else {
            $description = "Error guessing CSE name"
        }
        
        [PSCustomObject] @{
            GUID = $guid
            Description = $gpeName
        }
    }
}