If you ask many companies they may not think about their data being multi-cloud. The thinking is more about their application estate.
On pressing you will be told that they may have windows filers, have a NAS or SAN, perhaps are using object storage either on-premises or on-cloud with something like Amazon S3, use email, perhaps outsourced to someone like Google, which also provide their employees with a cloud drive, are using a cloud based CRM such as Salesforce and perhaps a raft of other cloud based Apps that have file storing capabilities.
Congratulations, that is what a multi-cloud data company looks like in 2019 !
I have seen a lot of FUD on GDPR and Compliance recently, and a lot of non European firms paying lip service to offering GDPR compliance solutions, and when you take a deeper look, those claims fall down pretty easily.