I haven’t touched Windows 10 IoT in a long long time so I won’t be much help with that.
One way to maybe get there is to do a search for the LED’s used, the SK6218’s. Then figure out how to address them etc.
I don’t think Microsoft permit the sort of hardware access required to get Unicorn pHAT up and running. Although there appear to be some people getting WS281x LEDs to work over SPI.