Afaik this information is not available through any of the PowerCLI cmdlets nor through the APIs.
What you could do is to use the plink.exe command and launch a command in the COS that returns this kind of information.
The following script shows for example how to launch the dmesg command in the COS and captures the output in a PowerShell variable.
$User = <ESX-account>
$Pswd = <ESX-password>
$Computer = <ESX-hostname>
$plink = "<Putty directory>\plink.exe"
$plinkoptions = " -v -batch -pw $Pswd"
$cmd1 = 'sudo -u root /bin/dmesg'
$remoteCommand = '"' + $cmd1 + '"'
$command = $plink + " " + $plinkoptions + " " + $User + "@" + $computer + " " + $remoteCommand
$msg = Invoke-Expression -command $command
# Extract the required info from the $msg variable
...
Of course you need to set up sudo in the COS correctly to be able to do this!
