Google Cloud Storage provides an Object Lifecycle Management feature that can help automate data retention and deletion processes, ensuring compliance with data privacy regulations while minimizing storage costs.
Lifecycle Management: Object Lifecycle Management allows you to define rules that automatically delete objects after a specific period. This ensures that data is only retained for the required amount of time and is deleted once it expires.
Configuration: You can configure lifecycle rules to delete objects based on conditions such as the age of the object, the creation date, or custom metadata. This allows for precise control over the retention period of your data.
Cost Efficiency: By using lifecycle policies to delete data automatically, you can reduce storage costs, as you only pay for the storage you actively use.
Reference:
Cloud Storage Object Lifecycle Management

https://cloud.google.com/sql/docs/mysql/cmek
"You might have situations where you want to permanently destroy data encrypted with CMEK. To do this, you destroy the customer-managed encryption key version. You can't destroy the keyring or key, but you can destroy key versions of the key."

Reference:
Web Security Scanner supports categories in the OWASP Top Ten, a document that ranks and provides remediation guidance for the top 10 most critical web application security risks, as determined by the Open Web Application Security Project (OWASP). https://cloud.google.com/security-command-center/docs/concepts-web-security-scanner-overview#detectors_and_compliance

* 4. Publish the attestation to your public web page.
Explanation:
Generate Supply Chain Levels for Software Artifacts (SLSA) level 3 assurance by using Cloud Build: SLSA is a framework for ensuring the integrity of software artifacts. By using Cloud Build, you can automate the build process and generate SLSA level 3 compliance, which includes verifiable build steps and provenance.
View the build provenance in the Security insights side panel within the Google Cloud console: The build provenance provides a detailed history of how the software was built, including the source code, build process, and any dependencies. This information is accessible through the Security insights side panel in the Google Cloud console, allowing you to verify the integrity and authenticity of your software artifacts.
Reference:
Supply Chain Levels for Software Artifacts (SLSA) documentation
Cloud Build documentation
Security insights in Google Cloud console

VPC Peering is between organizations not between Projects in an organization. That is Shared VPC. In this case, both projects are in same organization so having VPC Service Controls around both projects with necessary rules should be fine.
https://cloud.google.com/vpc-service-controls/docs/overview