the vga arbiter stuff went away with UEFI based cards (about 2 years ago), consumer level cards now work without issue.

NVIDIA attempt to detect the VM and artificially disable the driver, but works perfectly if you tell KVM to hide the fact it's a VM (requires a flag to be set in the config).

the technical difficulty of pci passthrough consists of clicking "add pci device", then selecting your graphics card from the list.