[hardwaresofton]

Sorry the offline there is "offline-first", you need offline-first (AKA modern PWA type technology/architecture) for websites to work well in patchy internet/etc. The "offline-first" phrase/terminology is well known in frontend circles but maybe not as widely as I thought.

Generally offline-first/PWAs can be made "installable" by setting metadata on the page that hosts them and doing other things.