[zamadatix]

Post restriction there is no such thing as allowing network requests (same origin or cross origin) without opening a side channel which can work around said restriction (e.g. timing). However pre restricted mode there is no reason to restrict anything be it same origin or cross origin.

[aeharding]

Pre-restriction would have to disallow running javascript in that case. Otherwise an app could save data to localstorage, refresh the page programmatically (or wait for the user), and then transmit.

[zamadatix]

Or rather have the browser treat the no-network session period with private window logic where the session is deleted if the no-network browsing session ends or dies (e.g. incognito puts a virtual session data container in RAM). That would even allow the app data (prior to triggering the mode) to stay cached without risking side channels with future resource loads.

[pattyj]

The whole premise was to return to the pre-web 2.0 days but have the option for a user to enable modern web app capabilities. Which your idea would be a step towards.