Google secures more income by letting 1,000,000 stupid crypto currencies use GCP for infrastructure and by search related revenue than it would from "inventing" google bucks. There's no novel technology side to block chain for Google inherent in currency.
If they did a non repudiation chain rooted in an HSM with no proof of work or stake, for tiny per million transactions fee, and let everyone do public non repudiation transactional ledger, THAT would be interesting. No crypto currency. Good crypto in verified chain state which doesn't demand the heat death of the universe to compute. And at scale.