k3s author here. With user namespace and rootless support it is getting closer to k3s running in crostini, but nobody is really working on this. I was a big fan of crostini when it came out but the insistence on lxc and user namespaces makes it too limited and wouldn't recommend it if you work with containers.

unfortunately not.

figuring this out would make a lot of people happy, but it doesn't rank highly for our current use cases versus other work.

https://github.com/kubernetes-sigs/kind/issues/763