Is it permissible for a resident in Sweden to pray and fast according to the time in Saudi Arabia, or a nearby Arab country, or his country of origin?

The people of Sweden and its environs have two situations:

First Situation: If night and day alternate within 24 hours, they must pray and fast according to their legally prescribed times.

Second Situation: If night and day do not alternate within 24 hours, they must perform the five daily prayers within 24 hours, estimating their times and the times for fasting by referring to the nearest country where the times are distinct. Whoever finds fasting difficult due to the long daytime hours is permitted to break their fast and make up for it on shorter days. If some prayer times are distinct while others are not, then what is distinct should be prayed at its time, and what is not distinct should be estimated. It is permissible to combine the Isha prayer with the Maghrib prayer by performing it early (Jama' Taqdim) if waiting for its time becomes difficult.