FWIW it's not too difficult to convert a docker image to a VM rootfs. See rootfs_builder[0] for example.
I'm currently working on a wrapper for QEMU that has docker-like semantics for pull/run/start/stop/exec/etc, but it will pull docker images from docker registries and convert them to qcow2 for you and run them in QEMU. It works on Linux and Windows and should run on MacOS and BSD eventually.