At the core it's just a website, if you are able to get online to require an age check, you'll be able to access the system to generate the tickets - aka, electronically signed certificates. >the app works on any device – phone, tablet, computer, you name it. -https://ec.europa.eu/commission/presscorner/detail/da/statement_26_817 [EDIT] Oh, and the phone app should AFAIK, work offline, kinda in the same way a 2FA code app does.