I'd argue nothing is "fully" safe against zero-days - this is the nature of zero-days. But GOS takes more security precautions than stock Android, so by that m

I'd argue nothing is "fully" safe against zero-days - this is the nature of zero-days. But GOS takes more security precautions than stock Android, so by that metric there is a greater chance it is unaffected by an unreleased zero-day. But like I said, there really is no way to know. That goes for Android, GOS, and iOS.