Most people in Iceland buy bitcoin using localbitcoins.com , and if they have AUR there is nothing stopping them from exchanging to BTC. AUR can be used as a middle man currency between ISK and BTC.
I have also seen people ask on Facebook groups if someone can sell them bitcoin.
There are some people in Iceland that mine bitcoin and sell to others, others have for some reason money abroad, since before the currency controls or they are living abroad and can move some money to foreign exchanges. The normal person living here can't wire transfer money to a foreign exchange to buy bitcoin because of the currency controls.