This scenario is so common and the list of disputed territories is so long that it should be a standard.

It could be a bit like the timezones, the locale, or the decimal point separator, or other things like that. It should be an option at the OS level that you can configure, not be forced into.

There should be a common database that you can integrate in your map, a bit like timezone historical records, and the user should be able to see the map as claimed by any given country/territory. By default this could depend on your location or locale but it should definitely be possible to always see the map as the other side of the dispute has it, and to configure your device so that it shows maps (for all map software on the device), from a given perspective.

That's not a new thing. Maps have been political for ages. Mandating the shape of border lines on maps has been a part of many border disputes.

Also, it's eye opening to read or watch news from other countries. There's a big country-specific bias in the selection of international news stories. This bias is a necessary evil, but it can have a huge political and cultural impact.

It should be marked as disputed, from both sides, like "agreed to disagree".

Think what would happen if the UK took back Hong Kong, or if Hong Kong declared itself independent. We - westerners - would all love that and accept it immediately. Would we have a problem then with Apple if they showed HK as a separate country?

That's not surprising given that borders are not in any way "reality". They are mutually agreed upon conventions that, well, not everyone agrees upon.

It should be no more surprising than having a British English dictionary and an American English dictionary, only with higher stakes.