A customer data platform (CDP) collects events and customer data from website, app, CRM and web shop, links them into one profile through identity resolution, builds audiences and passes them on to marketing and product tools. Marketing and product teams use it to personalise campaigns and follow behaviour. Segment is a well-known non-European reference point.
The sovereignty issue lies in three things. The first is the consolidated profile itself. The second is the identity linking: the way the vendor connects email addresses, devices and cookies is derived knowledge you do not automatically get back when you switch. The third is activation. When a CDP sends audiences to advertising and analytics services, personal data leaves your environment, often towards non-European parties. Consent and deletion requests have to follow that whole chain. The Data Act demands open interfaces and export in common formats from cloud services, which is a useful yardstick for profiles and connections.
When choosing a European option, look for a set-up in which the data stays in your own data warehouse, collection endpoints on your own domain within the EU, integration with your consent management, export of profiles and identity links, and an overview of every destination the data is forwarded to.