I used this to find symantec AV:
$computers = Get-ADComputer -Filter *
foreach ($computer in $computers)
{
$SymServices = Get-WmiObject -ComputerName $computer.Name Win32_Service -Property Caption -ErrorAction SilentlyContinue |where {$_.Caption -like "*Symantec*"}
if ($SymServices.Count -gt 0)
{
Write-Host "$($computer.Name) protected by Symantec"
}
}