Offers an alternate way for authenticated embeds to opt in for unpartitioned cookies. These headers indicate whether unpartitioned cookies are (or can be) included in a given network request, and allow servers to activate 'storage-access' permissions they have already been granted. Giving an alternative way to activate the 'storage-access' permission allows usage by non-iframe resources, and can reduce latency for authenticated embeds.
The Storage Access API currently supports authenticated embeds’ ability to opt in for unpartitioned cookies by requiring them to call into a JavaScript API. This creates latency as the process undergoes multiple network round trips, and it limits use cases by requiring the embedded resources to use an iframe.
Samples: https://storage-access-headers-demo.glitch.me
Explainers: https://github.com/privacycg/storage-access-headers