In some sense, Kubernetes is just a portable platform for running Linux services, even on a single node using something like K3s. I almost see it as being an extension of the Linux OS layer.
Though imagining the unholy existence of an init system who's only job is to spin up containers, that can contain other inits, OS images, or whatever ..... turtles all the way down.
Tech like Flatpak or Snap is closer to Docker than "machines" are — except that Docker has local, virtualized networking built-in as the IPC layer.