While I cannot comment on specifics, we are going to provide deeper, first-class integrations with other GCP products.
Yes, GKE would be great. If we could specify the source of an ENV in a Deployment as a Managed Secret that would be incredible and save us so much hassle.
while a bit of a toy still, might be of interest: https://github.com/masonwr/CloudSecret. basic CRD that maps google "managed" secrets to Kubernetes secrets.