Reindeer skins and sonic looms – Borealis music festival dives into Sámi culture in the Norwegian city of Bergen

Europe’s only Indigenous nation

This just depends on how far back you look, no? It's already a nebulous term, and ascribing it to the Sámi as if they're therefore somehow more indigenous than other peoples is othering them more than they already are.

I do think Sápmi is one of the more established "traditional" areas than elsewhere in Europe so I understand the idea of calling them indigenous.

That's totally aside from how awesome it is to celebrate such traditional (and endangered) culture through a modern interpretation of a festival.