We'd like to propose the updated packaging format for the Web to address multiple forms of distribution of pages and PWAs, needs of Physical Web, access to content while offline and hosting of content on CDNs...
It allows to pack multiple resources into a single file and sign it with publisher's certificate. Digital signature allows to validate authenticity and integrity of the package on the client device regardless of the delivery mechanism, so the pages loaded form the package can be given the claimed origin's treatment, together with green lock, scripting and network access.
The Content Index structure allows efficient load to resources by direct access to them w/o need to unpack the package, which is important for devices with limited storage.
Here is the initial Explainer, this builds on work of Jeni Tennison and others (Packaging on the Web)