Pretty sure they are indigenous and I would think their religion would qualify as an “indigenous religion”?
[0] https://en.wikipedia.org/wiki/Christianization_of_the_S%C3%A...
The Decline of the Sámi People’s Indigenous Religion http://www.laits.utexas.edu/sami/diehtu/siida/christian/decl...
I know this isn't a great answer, but "yes and no" -- it is certainly true that the Proto-Indo-Europeans brought with them Rigvedic religion. But that religion itself was syncretized with other beliefs across Central Asia and South Asia over quite a long period of time. While it is often dramatized as a "violent" invasion (no doubt reminiscent of later "violent" "Aryan" invasions), the truth is more bland, which is that the nomadic Indo-Aryans and their ancestors had a rich level of cultural exchange with more settled civilizations. Some of it by the sword, but some of it otherwise.