The data behind the Datenanfragen.de project. This contains a directory of contact information and privacy-related data on companies under the scope of the EU GDPR, a directory of supervisory authorities for privacy concerns, a collection of templates for GDPR requests and a list of suggested companies to send access requests to.
Would it make sense to add the companies behind these domains to your database? https://github.com/duckduckgo/tracker-radar/tree/main/domains