Retrieve your Intune tenant/account Id from a locally installed Intune certificate

Get-IntuneTenantId.ps1

using namespace System.Security.Cryptography.X509Certificates
function Get-IntuneTenantId {
    # Check if "using namespace System.Security.Cryptography.X509Certificates" has been run
    try 
    {
        $x509Store = [X509Store]::new([StoreName]::My,[StoreLocation]::LocalMachine)
    }
    # If not, add the required type accelerators
    catch 
    {
        $Accelerators = [PowerShell].Assembly.GetType("System.Management.Automation.TypeAccelerators")
        $Accelerators::Add("X509Certificate2","System.Security.Cryptography.X509Certificates.X509Certificate2")
        $Accelerators::Add("x509Store","System.Security.Cryptography.X509Certificates.X509Store")
        $Accelerators::Add("X509FindType","System.Security.Cryptography.X509Certificates.X509FindType")
        $Accelerators::Add("StoreName","System.Security.Cryptography.X509Certificates.StoreName")
        $Accelerators::Add("StoreLocation","System.Security.Cryptography.X509Certificates.StoreLocation")
        $Accelerators::Add("OpenFlags","System.Security.Cryptography.X509Certificates.OpenFlags")
        $x509Store = [X509Store]::new([StoreName]::My,[StoreLocation]::LocalMachine)
    }
    # Check the LocalMachine store for the Intune certificate   
    $x509Store.Open([OpenFlags]::ReadOnly)
    [System.Object]$certExtension = "1.2.840.113556.5.6"
    $certCollection = $x509Store.Certificates.Find([X509FindType]::FindByExtension,$certExtension,$false)
    $x509Store.Close()
    # If not found, check the CurrentUser store
    if ($certCollection.Count -eq 0)
    {
        $x509Store = [X509Store]::new([StoreName]::My,[StoreLocation]::CurrentUser)
        $x509Store.Open([OpenFlags]::ReadOnly)
        $certCollection = $x509Store.Certificates.Find([X509FindType]::FindByExtension,$certExtension,$false)
        $x509Store.Close()
    }
    # Check we have a certificate
    If ($certCollection.Count -eq 0)
    {
        Write-Error "Intune Certificate not found"
        return
    }
    # Make sure we have the current certificate
    [X509Certificate2]$ActiveCert = $certCollection | Sort ExpiryDate -Descending | Select -first 1
    # Convert the Oid into a string array
    $Oid = $ActiveCert.Extensions | Where-Object {$_.Oid.Value -eq $certExtension}
    $BitString = [System.BitConverter]::ToString($Oid.RawData)
    $StringArrayList = [System.Collections.Generic.List[string]]::new($BitString.Split("-"))
    # Remove the first two items
    $StringArrayList.RemoveAt(0)
    $StringArrayList.RemoveAt(0)
    # Reverse the order of the jumbled items
    $NewStringArrayList = [System.Collections.Generic.List[string]]::new()
    $NewStringArrayList.Add($StringArrayList[3])
    $NewStringArrayList.Add($StringArrayList[2])
    $NewStringArrayList.Add($StringArrayList[1])
    $NewStringArrayList.Add($StringArrayList[0])
    $NewStringArrayList.Add("-")
    $NewStringArrayList.Add($StringArrayList[5])
    $NewStringArrayList.Add($StringArrayList[4])
    $NewStringArrayList.Add("-")
    $NewStringArrayList.Add($StringArrayList[7])
    $NewStringArrayList.Add($StringArrayList[6])
    $NewStringArrayList.Add("-")
    $NewStringArrayList.Add($StringArrayList[8])
    $NewStringArrayList.Add($StringArrayList[9])
    $NewStringArrayList.Add("-")
    # Add the remaining items
    $NewStringArrayList.AddRange([string[]]$StringArrayList[10..15])
    # Join and return the string
    return $NewStringArrayList -join ""
}

# Example
Get-IntuneTenantId