I would ignore that blog post. It is from 2018 and for a different era of Istio architecture. If you look at the Telemetry API, you should be able to send information to Stackdriver. The key bits will be authentication. If you are running in GKE, this should not be an issue.
Yes. It is possible to integrate with Cloud Logging. You’ll need to set up default application credentials and pass in the project you wish to use via GCP_METADATA, but it should be doable.