To be fair many of these words would be needed for running a bare metal kube cluster.

- Some servers: you need servers to run a bare metal cluster.

- CoreOS: This is just a minimal OS that's designed to be PXE booted. Think of it as a docker container for a bare metal machine.

- Kuma: Multi-cluster mesh network. This makes it easier to write services that talk to `foobar:8080` and have it automatically fail over to other pods in other regions. I wouldn't use kuma, there's a few other options, but this is very helpful. Good service meshs will allow you to do Canary deployments. If you are multi-cluster than this sort of reliability is probably important to you.

But, an important part of this is that you don't need these if you're ok with running on another cloud's infrastructure.