I got the Razer Core X.

There is an issue where I have to plug it in right after windows starts to boot because the mac tries to disable the integrated graphics if it's plugged in when the laptop boots (which causes windows to not boot). But if you don't plug it in while windows is in the early boot stages then windows doesn't seem to want to identify it. Apparently this is solvable with a custom efi module but I haven't explored that yet.

Otherwise it works solid in windows. Pretty much the same performance as when the card was in my desktop.