On Magento Web Push Notifications Extension's Privacy Page you can request and collect all the privacy and GDPR related information that Magento Web Push Notifications Extension is providing.
The privacy policy by is a legal document or statement that discloses how Magento Web Push Notifications Extension gathers, uses, discloses, and manges their customers' data.
The basis for MageCube sharing, adding, uploading, hosting, accessing or sending personal data out of Europe. Vendors can also add a description of their own impact assessment for data transfers.