I believe you’re likely misunderstanding Google’s architecture.

The routing isn’t centralized, it’s distributed. The VPCs are a logical abstraction, not a centralized dependency.

If you have a region/AZ going down in your global VPC, the other ones are still available.

I think it’s also not that much of an advantage for AWS to be able to say its outages are confined to a region. That doesn’t help you very much if their architecture makes architecting global services more difficult in the first place. You’re just playing region roulette hoping that your region isn’t affected. Outages frequently impact all/multiple AZs.