Amazon/AWS has no use case for VFIO in Firecracker. They're open to the community adding support and have a community meeting soon, but I wouldn't get my hopes up.

QEMU can work -- I say can, because it doesn't work with all GPUs. And with consumer GPUs, VFIO is generally not an officially supported use case. We got it working, but with lots of trial and error, and there are still some problematic corner cases.