Some helper scripts.
sudo ./prepare_raspi_image_arch64.sh -i rpi3bp.img
sudo ./nspawn_boot.sh -i rpi3bp.img -m shell
sudo ./nspawn_boot.sh -i rpi3bp.img -m setup
sudo machinectl terminate rpicontainertmp
sudo ./copy_to_sd_card.sh rpi3bp.img /dev/mmcblk0