https://www.w3.org/TR/security-privacy-questionnaire/
2.1 What information might this feature expose to Web sites or other parties, and for what purposes is that exposure necessary?
None
2.2. Do features in your specification expose the minimum amount of information necessary to enable their intended uses?
Yes
2.3. How do the features in your specification deal with personal information, personally-identifiable information (PII), or information derived from them?
This feature does not deal with any PII
N/A
2.5. Do the features in your specification introduce new state for an origin that persists across browsing sessions?
No
2.6. Do the features in your specification expose information about the underlying platform to origins?
No
No
No
No
No
2.11. Do features in this specification allow an origin some measure of control over a user agent’s native UI?
This feature allows the origin to open an always-on-top window. The origin can specify an initial width/height/aspect ratio of the window but cannot set a position.
None
2.13. How does this specification distinguish between behavior in first-party and third-party contexts?
No difference
2.14. How do the features in this specification work in the context of a browser’s Private Browsing or Incognito mode?
No difference
2.15. Does this specification have both "Security Considerations" and "Privacy Considerations" sections?
Yes
No
The Document Picture-in-Picture window closes when navigating away, so the window won't exist for a non-"fully active" document
N/A