Let's world build!
Nifl commoners live in igloos, and many are nomads but there are some towns and villages. Their main industry is ice fishing, but there is a decent demand for clothing and other objects made from the bones and skins of the local wildlife such as seals, arctic foxes, snowshoe rabbits, etc. Often these goods will be traded with other nations and the fish caught will stay in Nifl to feed the people there. They also hunt, but a lot of their food is fish.
Muspell has a lot of warrior tribes that fight each other over territory and resources such as farmland or hunting grounds. Sometimes warriors from these tribes will be drafted into the military, Helbindi is an example. Muspell people in general are tough and hardy and what farmland does exist isn't very efficient, mostly only enough to feed one family. They are generally a nation of bandits who will pillage and invade for things they need or want.
Manaketes do not consider themselves loyal to any nation. They live in tribal hamlets across the world and many are mercenaries who will fight for whoever pays them. Manaketes that live in Muspell sometimes have problems with the warrior tribes attacking them for their valuables. Askr tends to try to forge alliances with its manakete tribes. Embla ignores theirs. There are not many manaketes in Nifl because it's too cold for them.