For GCP, it depends. GCP doesn't have a Nitro competitor, but they offer Tensor Processing Units (TPUs). TPUs are more of a competitor to nVidia chips, but they are still custom silicon in the sense of the GP comment.

GCP, AWS, and Azure seem to all be diverging in their specialization. GCP is focusing more on AI/ML/Big Data offerings while AWS is more security-aware, and Azure is more hybrid-cloud focused.

Here is an article about Azure at least: https://www.theverge.com/2020/12/18/22189450/microsoft-arm-p...

“Because silicon is a foundational building block for technology, we’re continuing to invest in our own capabilities in areas like design, manufacturing and tools, while also fostering and strengthening partnerships with a wide range of chip providers,” says Microsoft’s communications chief Frank Shaw.