Give me some tips on what type of building supplies/architecture are successful in arctic and subarctic regions.

Tree. Log. Not planks, but a log. The main thing is that it should be dry. And then there will be no mold. And yet - you can not remove the protective layer of the tree - mezdra. Now they are making a beautiful rounded log. But it loses its protective layer, so it is treated with various impregnations and paint materials

our Chukchi and Nanai, Nenets graze deer in the north and roam a lot. They still live in yarangs - these are warm wigwams made of deer skins. In the center of such a "house", a woman maintains a fire. Nomadic shepherds live in such conditions at -50C. Of course, in this case, we are talking about comfort, about the shower and the bathroom no longer. This is the life of primitive people.

They can't wash! They will simply freeze after losing their natural fat layer from the skin.

There is a problem - the delivery of logs, forests to the Arctic latitudes.
By the way, I was looking at Viasat Explorer how they build houses from thick long logs in Canada! In Canada, they know how to build beautiful wooden houses. What is in the photo is a house with insulation inside. His problem is the removal of moisture from the inside.