Package: linux-image-cloud-amd64 Version: 4.18+99 The "HW_RANDOM_VIRTIO" configuration setting is not currently enabled in the "cloud" flavour of kernel images.
KVM virtual machines set up by virt-manager (and possibly virt-install, I'm not sure) come with a virtual random device like that by default, and would benefit from the driver being available if they need a lot of randomness.