I'm trying to screw around with https://kubevirt.io/user-guide/operations/installation/ It says:

Kubernetes apiserver must have --allow-privileged=true in order to run KubeVirt's privileged DaemonSet.

How would I verify that on k3s? Is that just stuffed into the unit file like normal k3s config flags?

--kube-apiserver-arg=allow-privileged=true

same as any other apiserver flag

So just:

ExecStart=/usr/local/bin/k3s \
    server --cluster-init \
    --kube-apiserver-arg=allow-privileged=true\

you probably want a space before the backslash, and to make sure there’s an empty line after that since you’ve got a trailing backslash, but yeah essentially