The short version, which will also be true in the long version: no student data is ever sold or used for advertising. Parent reports are built from structured learning data, never from chat logs. Children's audio is never shared with parents or third parties.
The full GDPR privacy notice: controller identity, purposes and legal bases, data categories, retention, processors, international transfers, and your rights (access, rectification, erasure, portability, objection, complaint to the Datenschutzbehörde).