Update March 4, 2024: Since we published this article, Apple reversed their decision:

It appears to be a non-issue now for Europeans.

Web apps (PWAs) are not supported on iOS in the European Union (EU)

March 1, 2024: Web apps, or Progressive Web Apps (PWAs), currently don't work in the European Union (EU) for the iOS 17.4 beta. Apple is removing support for PWAs in Europe allegedly to comply with the Digital Markets Act (DMA) regulations.

Apple detects if the location is in the EU based on the SIM card.

In the EU, all PWAs open as regular web pages in all browsers, and these web apps no longer have isolated storage. EU users can create a bookmark of the site that can be accessed from the home screen.

For more information see the following article from Mashable:

Apple confirms: It's killing home screen web apps in the EU