A few people expressed interest in finding out how this went, so I thought I'd do a writeup of my experiences getting PCIe passthrough working with multiseat.
One of the more interesting things to note is that hot-plugging aside, it works fine with Vega, despite the card not being shown as resettable by the Arch wiki script.
I've mostly followed the Arch wiki, with additional sources linked throughout.
Multiseat enables multiple people to use the same computer simultaneously. This can reduce setup costs (you only need one motherboard, CPU, etc.) and improve resource utilization (if one seat is idle, the other can make full use of the CPU + memory). The only parts needed per seat are the screen, peripherals, graphics card and a USB soundcard (opt.)
PCIe passthrough allows you to connect on