> And last and not least, it's not that the attribution is hidden or unreachable for the people using the app. It's right there, shown on tap, first line in bold text, the link to it is always visible on the map.
The OpenStreetMap Copyright page [1] is pretty clear: "Where you use OpenStreetMap data, you are required to do the following two things: 1) Provide credit to OpenStreetMap by displaying our copyright notice. 2) Make clear that the data is available under the Open Database License."
The guidelines for attribution even suggest a text to use: https://osmfoundation.org/wiki/Licence/Attribution_Guideline... and this text is certainly not "Legal" linking to an Apple URL. As I see it, complying with the license would be putting "© OpenStreetMap contributors" at the bottom of your map view, but again, IANAL, just an OSM nerd.