Basically I have an Apple Thunderbolt monitor sitting in the basement (that I can't sell) I'd like to use as a secondary monitor. My current desktop system is old and I was trying to figure out whether it was worth trying to get an x570 motherboard with a thunderbolt port when I upgrade it.
As mentioned by others the USB Type-C port on the GPU isn't a thunderbolt port. I know that GPUs do some capability around rendering and outputting that within the system which is how Optimus works, though in that case there is also an integrated GPU and a Ryzen 3 system would not have one.