In the system or Summary windows display the mac address of the agent. This is good for offline as it will save it in the agent.
Here is some code for it:
$networkAdapter = Get-NetAdapter | Where-Object { $_.Status -eq 'Up' } | Sort-Object -Property 'InterfaceIndex' | Select-Object -First 1
$macAddress = $networkAdapter.MacAddress
Write-Host "MAC Address of the primary network adapter: $macAddress"
GoreloAction -SetCustomField -Name '$gorelo:asset.MacAddress' -Value $macAddress