And that Kubernetes deployments out there primarily run on Linux.
No, not all embedded systems run an OS. Linux is not an OS, it's a kernel. Ubuntu is an OS. Kubernetes is application software that runs on several operating systems, primarily ones based on the Linux kernel.
Ubuntu is not an OS, it's a Linux distribution.
Many do not. I've seen quite a few ARM processors running without any OS.
No, not all embedded systems run an OS. Linux is not an OS, it's a kernel. Ubuntu is an OS. Kubernetes is application software that runs on several operating systems, primarily ones based on the Linux kernel.