ChaosMonkey for k8s? Is there a kind of tool like ChaosMonkey specific for k8s that kill nodes and pods during office hours to train the team how to deal with issues and to harden the k8s cluster?

It is possible to create a script or program that kills random PODs, but if such a tool already exists then this will save time.
You can take a look at kube-monkey. According to the README, it randomly causes failures in kubernetes clusters.