But dont these apps require network access to function?
Some of TicketMaster’s API docs for this are publicly available so you can get an idea of how it works - https://developer.ticketmaster.com/products-and-docs/apis/pa...
I haven't seen a paper ticket in a long time.
On iOS, at least, local storage for web apps doesn't have guaranteed persistence. Safari can and will "randomly" clean up, usually if the device is low on storage. This happens less frequently for pinned PWAs but still happens.
If you need to absolutely guarantee that your thing will work on an offline mobile device, you have to use a native app.