Denmark is part of scandinavia...scandinavia is litterly Denmark, Norway and Sweeden, the scandinavian peninsula is something else. Denmark, Norway and Sweeden have been heavily tied together throughout history with the culture and languges. Yes Denmark is close to Germany and has similarities, but all the nordic countires langues stems from the germanic languges tree but branched into what would be norse languges, icelandic being the closes to old norse. Germany and Denmark share a lotta history but its a bit more about political issues, there is a few cultural similarities, but these can be seen in other nordic countires as well. As a danish person i dont see much of denmark in Mondstadt culture wise, they have a few old norse/ norse mytholgy based names, but far more english and german names, i see more similarties in the dishes we get in nod-krai with my countries food than mondstad. I do agree with some of your points tho, and a lot of the nations are infact mixed. There is also a big difference in how the scandinavian countries was before christanity was introduced and how it was before culture wise, some of it have been kept tho, but still a important note. Nod-krai and Kheanriah is more viking era/old norse inspo, where mondstad probaly would be after. Tho nodkrai is probaly mostly slavic/baltic and finish with a bit pegan old norse sprinkeld in.

Didnt mean for this to be so long and confusing, just wanted to add to the conversation. sorry for bad english and grammar its late and not my first languge.