Maps seem like a distinct failure mode of web apps. How do you load the map data on the website to navigate or orient yourself if you got lost outside the network coverage area?
It's easy. You can download data for certain areas you expect to be in offline mode and move all routing logic to app.
It has been done many times in many apps.
(ok, it only easy conceptually in reality it's quite big chunk of conscious dosign of app as a whole and no lesser chunk of actual work )
As far as I know, Google Maps used to not work outside of network coverage for like 15 years ? It already reached 1 billion user without the download area feature.
