If it was that simple, Google would have been the obvious choice. They have already started migrating to GCP and signed an $800 million dollar three year deal.
https://www.theinformation.com/articles/tiktok-agreed-to-buy...
https://www.theinformation.com/articles/tiktok-agreed-to-buy...
If it's one of a dozen places you advertise, that's fine. If you're trying to run a business where it's a core platform, you quickly run into the limits there.