Not private doesn't mean public.

Can google guarantee this data is not used to fuel their ad or other businesses in anyway ?

Can they guarantee US Law Enforcement Agencies(LEA) will not have access without due process and informing you ?

Can they guarantee LEAs from other countries will not given access to this data ?

Private = only you, and no one else, not even Google.

Google has had data leaks and hacks, yes. It’s not private unless you own it and control it.

If you send it to Google it is unequivocally not private.