Download and Install Windows Updates offline using the wsusscn2.cab file and Windows Update API

Download updates using PSWindowsUpdate module:

# Install PSWindowsUpdate module (requires internet connection initially)
Install-Module PSWindowsUpdate -Force

# Download updates to a specific directory
$downloadPath = "C:\Updates\Packages"

# Get missing updates and download them
Get-WUList -Category "SecurityUpdates", "CriticalUpdates" | 
    Where-Object {$_.Size -lt 500MB} | # Filter large updates if needed
    Save-WUUpdates -Directory $downloadPath