Getting GPU with fakeid working

I'm trying to get GPU acceleration working for my OSX Monterey VM, running on a Proxmox host OS. The GPU I'm using is a Radeon Pro WX 3200, which I understand isn't natively supported, but will work with a fakeid for a WX 4100.

For setting up the OSX VM, I've followed the guide here: https://www.nicksherlock.com/2021/10/installing-macos-12-monterey-on-proxmox-7/

That has got me OSX up and running without any GPU.

I did at one point have the GPU passed through to OSX with no fakeid, but there was no hardware acceleration. (It was outputting the screen I have attached to the GPU but still showed 3MB graphics memory and things were still as sluggish as without the GPU). I'm not sure how I managed that though, as after messing about with trying to get it working properly I can't get it to boot with the GPU attached at all.

The deviceid for my card (WX 3200) is 6981. The deviceid for the WX 4100 ( which I understand works, see https://www.tonymacx86.com/threads/new-radeon-pro-wx-3200.279988/page-3#post-2146461 ) is 67e3.

If I set the card with a fakeid in the QEMU args:

-device 'vfio-pci,host=0000:05:00.0,id=hostpci0.0,bus=ich9-pcie-port-1,addr=0x0.0,multifunction=on,x-pci-device-id=0x67e3' 

It won't even boot to the OpenCore loader. If I supply the rom of a WX 4100 as well:

-device 'vfio-pci,host=0000:05:00.0,id=hostpci0.0,bus=ich9-pcie-port-1,addr=0x0.0,multifunction=on,romfile=/usr/share/kvm/radeon-wx-4100-188583.rom,x-pci-device-id=0x67e3' 

It still won't boot to OpenCore.

If I pass through the card with no fakeid, the OpenCore loader boots, but when trying to boot OSX I just get the apple logo with the loading bar stuck at the start.

If I also have the display set to vmware (rather than none), so I can connect via VNC, I just get a black screen when trying to boot OSX.

From the EFI I can see the PCI info for the card:

00 01 00 00 => 1002 6981 00 01 00 01 => 1002 AAE0 

(AAE0 is the audio for the card).

So I've added the card to the config.plist with the deviceid for the WX 4100 (I think, I copied the settings from the screenshot here https://www.tonymacx86.com/threads/new-radeon-pro-wx-3200.279988/page-3#post-2159138 but changed the PciRoot):

https://preview.redd.it/16fekmz8lh481.png?width=1026&format=png&auto=webp&s=cdcb4f4662faaa58a587e6184738159b28a75ce2

<key>DeviceProperties</key> <dict> <key>Add</key> <dict> <key>PciRoot(0x0/Pci(0x1,0x0)/Pci(0x0,0x0)</key> <dict> <key>device-id</key> <data>E3670000</data> </dict> </dict> ... 

But it's not helped at all, and still gets stuck at the Apple logo. Can anyone advise if there's something obvious I'm doing wrong, or suggested steps for troubleshooting?

Cheers