[funkjunky]

That page mentions that it supports the google-cloud-python libraries, which are the primary GCP gRPC client libraries for Python. The Apiary service-discovery library you are referring to is called google-api. The new GAE version doesn't support the old GAE-only libraries, like memcache, datastore, etc. These older services only worked with GAE, and therefore weren't portable to other services, which they are in the process of replacing. If I recall, the old version didn't support the google-cloud-python libraries either, so it's good to see that they are moving in that direction. I could be wrong about that though.

In short, it looks like you have access to the main GCP gRPC libraries. You don't have access to the GAE-only service libraries.

Disclaimer: was former GCP customer support.