Svalbard is known as a place where nobody is born and almost nobody dies. Expecting mothers are flown to mainland to give birth. There are no homes for the elderly. When you retire you move somewhere else. It's a place where you either work or study.

This is an issue not only in Svalbard but in much more populated places in northern Europe, some like Luleå, Sweden have substancial muslim minorities. As far as I know the recommendation is something like this: If you live where you cannot tell the difference between night and day, use the sahur/iftar times of the closest location where it is possible to tell the difference between night and day.

This usually mean fasting for 22-23 hours during summer and fasting for one-two hours during winter. Not very surprising a lot of people find this less useful, i.e. too hard challenge in summer and no challenge at all in winter, and chose to follow the schedule of Mekkah or their ancestral homeland instead.

I also know some muslims who just skip fasting altogether when Ramadan is in the summer months, also the time when people in Scandinavia finally get to enjoy life after the long harsh winter. Many people must take their yearly five weeks mandatory vacation in June or July.