Nonetheless I can cite the appreciable attempt to mix one's own culture with the songs (although it is a little too anchored, in KEiiNO and Alessandra, to the concept of Norse mythology).
That link isn't as strong as some think. Keiino's 2019 entry mentions northern lights, demons and fairies, but there is no reference to a specific mythology. (Another MGP song "Hammer of Thor" had that of course.)
Like Keiino, Alessandra's lyrics refers to general mythology and might as well be about ancient Greece or any other culture. The music style isn't particular Norwegian either - "Queen of Kings" is more of a pirate anthem, and Norway isn't know for producing a lot of 17th century pirates.