GCP has a lot of customers. But you wouldn't know the companies that do, unless you worked there and wanted to leak it, or it publicly comes out. Eg it's been publicly acknowledged that Apple uses GCP for iCloud, https://www.cnbc.com/amp/2018/02/26/apple-confirms-it-uses-g... , and Home Depot is another that's used as a case study, https://cloud.google.com/customers/the-home-depot but most customers don't want to make a big deal about being on GCP as it's none of our business who's hosting them.
GCP has a lot of customers. But you wouldn't know the companies that do, unless you worked there and wanted to leak it, or it publicly comes out. Eg it's been publicly acknowledged that Apple uses GCP for iCloud, https://www.cnbc.com/amp/2018/02/26/apple-confirms-it-uses-g... , and Home Depot is another that's used as a case study, https://cloud.google.com/customers/the-home-depot but most customers don't want to make a big deal about being on GCP as it's none of our business who's hosting them.