As I understand it, there's linux running on the Google Cloud hardware but the virtualized networking and storage stacks in Google Cloud are google proprietary

As I understand it, there's linux running on the Google Cloud hardware but the virtualized networking and storage stacks in Google Cloud are google proprietary and largely bypass linux -- in the case of networking see the "Snap: a Microkernel Approach to Host Networking" paper. In contrast, it appears that Oxide is committing to open-source the equivalent pieces of their virtualization platform.