Just a thought, but perhaps you could use a VM to run an older Windows in it. Virtualbox is free
No need for VirtualBox, Windows 10 already comes with Hyper-V 2016 which at least in the tests we did performed notably better than VirtualBox.
The drivers I used (WinRT) for this hardware would not work with Windows 10
Not surprising. WinRT is ARM only, not x86/x64. Windows drivers are platform-dependant.
as well so I spent the last three days porting my code to use Labview's generic driver. Once I get the GPIB controller working, I can run everything under 10.
First, let me say that we use Agilent/Keysight GPIB controllers at work (and I use them at home as well) so I have no direct experience with the NI GPIB Ethernet boxes and only little with the NI-VISA software, so I don't know if this works with your NI gear.
However, Agilent I/O Libraries support a mode where they can act as a 'server' where it just acts as a remote interface for one or more other I/O Lib installations on other PCs. So if this was an old HP GPIB-Ethernet adapter like the E2050B then I'd setup a Hyper-V VM in Windows 10 which runs plain Windows XP and the last version of the Agilent I/O libraries that supports the E2050B (IIRC 14.0), and then connect with the latest Keysight I/O Libraries under Windows 10 to the I/O Libs in the VM, which connect to the E2050B. This works completely transparent and from from your Windows 10 host it would look like any other instrument that is connected directly.
I wonder if NI has a similar feature in its software so you could just run the old NI-VISA on an old XP in a Hyper-V VM and have the latest NI-VISA software use it as a remote interface.
Just a thought.