> ... launches those apps in crosvm sandboxes in seconds.

Technically true, but the initial VM launch is not all that quick. E.g., on a Pixelbook i7 launching a terminal session without the VM started, it takes about 20 seconds for the VM itself to initiate, and another 30 seconds for things like volume mounting and starting the container running Debian, for a total of 50 seconds.

Subsequent launches once the VM is started are much quicker, just a few seconds.

> I looked for but couldn't find ChromeOS GCP instances

You're looking for Container-Optimize OS: https://cloud.google.com/container-optimized-os/ , which is Chromium OS based.

It's the default OS for e.g. GKE nodes, so Google probably runs pretty large numbers of them.