Boot Camp install of Windows 10 gets stuck on first logo and spinner
So turns out the problem for me is booting up with an external gpu attached. In the photo you can see the little thunderbolt cable on the left. Even though it works fine booting into macOS, it doesn't work when booting up into windows for some reason. 

This freeze happens even after the Windows OS is installed. The workaround is to unplug the egpu and re-attach post bootup. 

For anyone else coming across this, my egpu is a mantiz venus w/ rx 570.