https://www.pcgamer.com/complex-threadripper-hack-gets-intels-thunderbolt-3-working-on-amd-hardware/

Twitter via Wendell Wilson/Level1Techs. Click for original.

Gigabyte had grand plans of enabling Thunderbolt 3 support on its X399 Designare EX motherboard by way of an add-in card, which users could buy and plug into a header. There was only one problem—Thunderbolt is proprietary Intel technology, and Intel hasn't certified any implementations on Ryzen or Threadripper. We don't know the full situation, but the roadblock appears to be more of a licensing issue than a technical one.