>>107063764
Ah, I was using it wrong. You have to:
$ bwrap --ro-bind / / --dev /dev --proc /proc --tmpfs $HOME --unshare-all bash
But as expected, no more GPU:
$ vulkaninfo
'DISPLAY' environment variable not set... skipping surface info
ERROR: [Loader Message] Code 0 : setup_loader_term_phys_devs: Failed to detect any valid GPUs in the current config
ERROR at /var/tmp/portage/dev-util/vulkan-tools-9999/work/vulkan-tools-9999/vulkaninfo/./vulkaninfo.h:247:vkEnumeratePhysicalDevices failed with ERROR_INITIALIZATION_FAILED