There had been North African Slave raids on island OTL in the early modern era. Maybe the pirates permamently establish bases and eventually subjecting the Iceland population and founding an Emirate.
The population of Iceland was quite small at this time. Maybe a North African slave ship wrecks on Iceland and the survivors manage to stay and introduce the religion that way.
It still numbered in the tens of thousands and they were Christian enough to hold witch trials and go along with what the Danish clergy asked them to.
Or just one defeated the Santiago-Asturias and them sailed very north for some reason
That could be incredibly interesting (though bordering on the implausible, unless a significant chunk of Europe converts to Islam I don't see how it could reach northern Europe; but then again, it made it all the way to Indonesia even before the age of sail, so it isn't entirely impossible). The distance and relative isolation from the rest of the Islamic world would most likely result in a very unique culture/religion. I could see it diverging a fair bit from "regular" Islam depending on how exactly the conversion happens and just how much contact they have with other Muslim polities.
It could be!
Some Changes are for mere necesity, like Ramadan on Summer Months and longer Ramadan on winter ones, some considerations what to eat on harsh winter and mostly that, might not change much or at all either
