>and home users only got the ability to pass through a subset of consumer-level nVidia GPUs (which IIRC doesn't apply to laptops, so you're still stuck there)
That's not quite correct any longer. Nvidia now supports passthrough on all consumer GPUs that work with their current driver. This also includes laptops with Nvidia chips and they've been actively fixing bugs and compatibility problems in every driver release since then.
Before official support the Nvidia kernel driver just crashed Windows with a BSOD on my laptop. Then it suddenly worked, but I wasn't able to open the control panel and worse, the HDMI output didn't work. The driver after that fixed those problems. The only things still not working are voltage and power monitoring, although temps work.
Additionally, and I know this is a special case, performance is actually better than on bare metal. The reason is that in a VM I can inject a modded VBIOS with higher power limits and that gives me a nice 15-20% boost. I can't do that on bare metal because the VBIOS is stored in the system firmware and accessed via an ACPI method by the driver. Sadly only signed firmware can be flashed directly and even a flash programmer wouldn't help because at boot the firmware is verified and overwritten by a clean if it doesn't pass. This doesn't matter for desktop chips, but on a laptop you can actually get way more FPS if the power limits are ridiculously low by default! In my case I went from 30W or so to 75W (PCIe limit) and even though clocks stayed the same, games ran much faster. I guess it was hitting power limits and throttled, but didn't down lock because clocks only depend on voltage and available voltage level on temperature. I also ever saw power limits (via AfterBurner OSD) in furmark, but apparently it was also limited in other workloads without indicating it. With the modded VBIOS I don't even see power limits in furmark. It's either voltage or temps.