Le Pen might actually have an outside shot at winning Mayotte, which is the only Muslim majority department. Albeit with very unique circumstances.
Other than that, you are never going to know for sure because it's not legal to collect those sorts of statistics - perhaps assume based on the results of certain areas known to have large populations with immigrant backgrounds. But even then, RN do quite well in some of the pavillonaire suburbs on the North-Eastern edge Seine-Saint-Denis or in parts of the Val d'Oise, and those are still areas with pretty large Maghrebin origin populations.
Though Le Pen would be lucky to come with 25 points of Macron, the RN have been stagnating at best since 2017 - so who Muslims vote for is a pretty safe bet.
1. What are the unique circumstances of Mayotte?
2. I know the Census is forbidden from collecting ethnoracial statistics in France, but aren't there exit polls with religious crosstabs? I know that exit polls can be trash with crosstabs, but still.
3. I would assume that most RN voters in those Maghrebin-heavy suburbs are people of native French ancestry?
