I can tell you with 100% certainty that Google the user facing products like Google Search and Gmail don’t share hardware or infrastructure with GCP and they do

I can tell you with 100% certainty that Google the user facing products like Google Search and Gmail don’t share hardware or infrastructure with GCP and they don’t just repurpose servers between the two. This is like the same myth that AWS started because Amazon decided to sell “excess capacity” from Amazon Retail to bootstrap AWS. That never happened either.