These discussions of religion really do not take points like this and geography into account as much as you think.
Although more Islam gets into Europe more likely you see less rigid sects like one in Muslim Spain who I think drank alcohol.
Even in any pod that involves Islam eventually taking over bunch of Europe I imagine the religion has more sects form of wide variety to point Arabs in Saudi consider Europeans more of “apostates” and “heretics” more so then Iranians.
Issue with Islam is “low key” bias and excessive favoritism towards Arab people and language. What hell would Norse language even look like with that alphabet.
Some Arabs especially from Arabia and Levant still see themselves as “heart” of Islam and most “true Muslims”.
Christianity wasn’t even that extreme or no where near as much favoritism towards Greek and Latin culture as Islam to Arabs
I think thats very much an exaggeration to say the least. Sure with Arabic being the liturgical language you're of course going to see some form of Arabo centrism when it comes to religion, but to say it extended to the point of viewing peoples who converted to Islam as 'less muslim' is just frankly untrue, that whole debate died with the overthrowal of the Umayyad Caliphate and even with them the arabo centrism of that dynasty is very much overstated.
Persians are really second only to Arabs when it comes to contribution to the Islamic corpus and Persians were considered people of high culture, hence why Persian styles, government and ideas were very readily embraced by Arabs. As a small example, belly dancing which is something we often associate with arabic cultures was in fact originally persian.
Would the Arabs look down on Western Europeans even if they converted to Islam? Yes of course they would as they did OTL when they were christan anyway and usually for reasons besides religion, in contrast to how they viewed the Eastern Romans the Muslim arabs saw the Franks as backwards and barbaric people.
In short, the Arabs of this period and their views on different peoples was usually affected by how civilised they perceived the culture to be and though religious values did sometimes come into play, its important not to conflate that with a sense of inate arab superiority in religious terms.
Modern arabs is a whole different can of worms I won't get into.