shared this link on another reply, but google moved away from gvisor to hypervisor for cloud run. It won't be long before they do for GKE as well
https://cloud.google.com/blog/products/serverless/cloud-run-...
https://cloud.google.com/blog/products/serverless/cloud-run-...
But at the end of the day, there is a line in the sand around hypervisors vs proc/kernel isolation models. I challenge you to go to a financial or medical institute and tell their CTO "yeah, we have this super bullet proof shared-kernel-inproc isolation model"
The first question you'd get is "Why is this not just part of upstream linux?" Answer that question and realize why you should just use a hypervisor.