You can!

KinD[0] is a project to do just that, although production workloads are an explicit non-goal.

[0]: https://github.com/kubernetes-sigs/kind

> So why not run kubernetes nodes in containers?

Plenty of usecases are already covered by that. Also, running containers in containers is also a thing.

It's containers all the way down.

Since the parent is running on GKE, they’re already doing that. Postgres in a (kube) container on a (GCE) VM in a (borg) container on a computer.