Windows 10 had installed some default drivers but the volume control didn’t have any control over the speakers plugged into either the front or rear audio out. Without getting all the Windows drivers installed in one go from Bootcamp, the only other thing I missed initially (before finding this post), was Audio drivers.
As long as you can get to the boot screen and pick which partition to boot from then this is ok (although since I’ve also added a PC version (unflashed) of an Nvidia 750 Ti, whenever I want to switch OSes, I have to switch my monitor cable between the stock Mac ATI card, and then switch it back to my 750 Ti after I’ve picked which OS I want to boot). to select to boot back to MacOS from Windows. The main feature I’m particularly missing is the Bootcamp systray app in Windows to allow you to pick your boot drive, i.e. The Bootcamp driver download from Apple though is no longer supported on a 2008: Windows 10 runs surprisingly well on my (new) Mac Pro 2008.