Have you tried using software inventory? We have a couple of Dell devices that have Thunderbolt ports and I'm using a query to search for Scanned Application "Thunderbolt(TM) Service" and that's doing the trick for us. Otherwise I don't see anything in hardware inventory that would show that information. Might be a good idea for a future release if that information could be pulled in.
Yes, we have Lenovo and can identify software related to the Thunderbolt ports but I'm still looking to see if I can identify the ports from a hardware perspective.
When looking at the Properties of a device in Device Manager, the Details tab seemed to offer an opportunity to do this by looking at the device property and the related value but I have not been successful so far.
Thank you for the suggestion!