Lets play a fun little game!
Since vast areas of land are still most likely unexplored, do you think there are isolationist villages and cultures within the black areas of Scandinavia? The red areas are only the KNOWN world - the areas that have contact with one another! But in the chaos of y0 and the trollocapypse, people must've fled all over the place, seeking refuge in the countryside and the wilderness. A return to viking aesthetics would've hardly been the first thought to everyone, would it? And in the case of Sweden, they have no mages to help influence their religion or faith, and even in Finland and Norway we have no evidence pointing toward the kind of dreamwalking that Reynir was up to, so contact with the rest of the world would still be very limited.
So... the game is to make up wacky cultures and locations! It's like making OC's, but with groups of people instead.
For example, what would happen if a cult of crazy Christians were stranded in Lappland, still thinking that the Rapture is coming to pick them up? Or if there was a colony where only young children survived, having to re-discover culture, order and making-sense-of-the-world all over again? A remote mental warden somehow making it through, or a bunch of survivors holed up in a gigantic chicken farm where they had to co-exist with endless chickens for eternity, afraid to step outside due to the disease, eventually creating a chicken religion and a chicken-based world view as they were driven to madness across the generations? Or maybe just a fairly normal little village, that never the less had to come up with their own explanations to explain the madness of the world.
Lets just have some random fun