How can a Muslim fast the days commanded by the Prophet (peace be upon him) in northern Norway, where the daytime lasts 23 hours and the sun does not set, given the significant differences in prayer times between applications and the websites of Islamic centers, and can he follow the timing of Mecca or any other timing?

What is understood from the question is the hesitation between the timing of the Islamic Association in Norway's website and other timings, and that the Association's timing has a very long duration between dawn and sunset. What appears to be the case, and Allah knows best, is that if there is an Islamic center in the city where you reside, you should pray and fast according to their timing, as they are more knowledgeable about the reality and situation there. If there is no Islamic center in your city, then you must follow the timings of the closest city to you where night and day alternate within twenty-four hours. This is the city you mentioned, and its timings are according to the Islamic Association in Norway. It is especially important for you to follow this city for two reasons: First: it is the closest place to you where night and day alternate within twenty-four hours. Second: the Islamic Association in Norway is more knowledgeable about your situation. Therefore, we advise you to follow the timings of this city, even if the fasting period is long, as long as the sun rises and sets within twenty-four hours.