I've dropped a couple follow-up questions in our DM thread.
I believe you have a workaround for the issue related to pulumi-gcp#88. I added an explicit note on that in
https://github.com/pulumi/pulumi-gcp/issues/88#issuecomment-482334587.
It sounds like you may now be hitting unrelated issues in GKE/GCE related to networking configuration. Happy to help look at these in DM.