Wendell wrote an draft of instructions in the following thread how he was apparently able to pass through a MIG instance of an Nvidia RTX Pro 6000 Blackwell Workstation Edition to a virtual machine with kvm/libvirt.
I am trying this too, but have been unsuccessful so far. You mileage may vary. The problem I am facing is that the GPU does not advertise SRIOV capabilities with MDEV and even when I load the mdev kernel module and spawn MIG instances I have no MDEV devices I could pass through.
My guess is that passthrough to LXC would be very similar to how it works for kvm/libvirt. If you manage to make this work please let us know. If you have questions feel free to ask, though no guarantee I’ll be able to answer them.