How to: proof of concept only, generates random serial numbers, headlessly, and quits right after.
docker run --rm -it \
    --device /dev/kvm \
    -p 50922:10022 \
    -e NOPICKER=true \
    -e GENERATE_UNIQUE=true \
    -e DEVICE_MODEL="iMacPro1,1" \
    sickcodes/docker-osx:auto