For physical zone separation you need to check the `supportsPzs` attribute when listing the zones (e.g. https://cloud.google.com/compute/docs/reference/rest/v1/zone..., but you should be able to find many other places where this attribute is surfaced).

It says "reserved for future use" but other docs mentioned "physical zone separation": https://googleapis.dev/java/google-api-services-compute/alph...