With Graph API we are only getting 1000 devices

Ashish_Arya This script indeed does not add "paging" to retrieve additional devices if they exist. This is evident because it uses the "Get-Win10IntuneManagedDevice" function inside the script, which only does one call to the Graph API endpoint. You could potentially modify this function to do paging, on the other hand, there's a Graph PowerShell module nowadays which could potentially be used to replace parts of this script's custom code with simpler out of the box cmdlets.

The code responsible for only returning a subset is this:

       else {

            $Resource = "deviceManagement/managedDevices?`$filter=(((deviceType%20eq%20%27desktop%27)%20or%20(deviceType%20eq%20%27windowsRT%27)%20or%20(deviceType%20eq%20%27winEmbedded%27)%20or%20(deviceType%20eq%20%27surfaceHub%27)))"
	        $uri = "https://graph.microsoft.com/$graphApiVersion/$($Resource)"
        
            (Invoke-RestMethod -Uri $uri -Headers $authToken -Method Get).value

        }

For more information on how paging works in Graph API, you can have a look at this URL.