Not saying you're wrong, but I'm having a hard time finding GCP products that had paying enterprise customers at the link you provided, at least none with Greek names.
Not there yet, but Hades is a Greek name: They should name a product Hades and then kill is just so gcemetary has, you know, appropriate oversight & leadership.
Kubernetes, the technology that Anthos manages for users, is open source. The code base that does that managing is not open source afaik.