Explanation on the iframe attributes used by vulp.
The vulp iframe embed uses a small number of attributes that are required to obtain the full functionality.
xr-spatial-tracking value is inside the
allow attribute in order to enable fast rendering of 3D models.
fullscreen value is inside the
allow attribute such that it is possible to add fullscreen functionality in the future. It is not strictly required at the moment.
no-referrer-when-downgrade referrer policy is required to obtain the URL of the parent page such that vulp can show a QR-code to that page.