Google cloud implementation

We've had several starts and stops on implementing the Gen3 cloud automation, and want to verify that our initial assumption is correct. Specifically, we were under the assumption that we could implement on GC as opposed to AWS (albeit calling AWS). However, the Gen3 cloud automation doc seems to imply AWS, and the architecture diagram has AWS wrapping the instance.
Is an AWS instance necessary to implement, and if not, are there any GC specific docs available? Also under GC, what is the recommended VM to use (we chose E2, but not sure if this is correct)?