I am having a hard time finding documentation on gcp apis. Is the right way to get the information is to look at Terraform documentation when it says

This Pulumi package is based on the google-beta Terraform Provider.

?

No, you should use the Pulumi Registry as your first stop: https://www.pulumi.com/registry/packages/gcp/api-docs/ You can use the TF docs as a backup if for some reason the registry docs are not sufficient.