As a quick aside, the term Aryan was also co-opted by the Nazis. It originally referred to the Indo-Europeans as whole, and well the Swastika was present in European art until the early modern period namely as a form of repeating pattern for say rugs.
Any symbol they would have chosen would have ended up as the Nazi symbol. Just like the name Hitler or that specific mustache style.
But the swastika specifically ending as the symbol you can mostly thank to Heinrich Schliemann and Émile-Louis Burnouf finding swastika adorned pottery at a Troy excavation in the 1870’s, and declaring them to be the ancient symbols of the Aryans. https://humanjourney.us/language/external-symbols/swastika-the-hidden-power-of-a-symbol/
As a quick aside, the term Aryan was also co-opted by the Nazis. It originally referred to the Indo-Europeans as whole, and well the Swastika was present in European art until the early modern period namely as a form of repeating pattern for say rugs.