They describe themselves as Norse folk, which they're pretty faithful exponents of.
In broader terms, I'd put them under the neofolk umbrella, which I don't blame them for rejecting, as it's a historically problematic genre which had a Nazi problem early on (like some parts of early black metal and dungeon synth), although the overwhelming direction of the genre now feels more hospitable to anti-fascists than the opposite (as one would hope), thanks to the work of organisations like A Blaze Ansuz (https://antifascistneofolk.com/).