Running unikernels under kubernetes diminishes some of their security benefits, however, a lot of organizations still have heavy kubernetes installations so these are some ways you can still run unikernels in k8s.
Pre-requisites
You need access to hardware virtualization. If you are in the cloud the best way to get that is through NanoVMs Inception available on the AWS market. https://aws.amazon.com/marketplace/pp/prodview-lwk72eg6wfo3i. This will allow you to run kube-virt on plain old normal ec2 instances like an ec2.small without having to resort to expensive metal instances.
If you don't want to do that you'll either need a real physical computer or use metal instances.