Elfdalian is a distinct language with ancient roots

[Duncan Head]

No, not spoken by elfs...

https://www.theguardian.com/world/2024/nov/03/runes-prove-elfdalian-is-distinct-ancient-nordic-language-say-researchers

[Imperial Dave]

 

[Andreas Johansson]

You might want to peruse the WP article for a less sensationalist (but much more detailed) take.

The equation of difference in vocabulary to mutual unintelligibility is a bit weird. The intelligibility between Swedish and Norwegian is much higher than between Swedish and Danish not because Danish is more out there vocabulary-wise, but because the pronunciation is out there.

The bit about the Swedish "Empire" and its supposed intolerance for Germanic varieties is a bit stupid. Elfdalians who had to do with Standard Swedish bibles weren't really treated any different than Savonians or South Estonians who were made to do with Standard Finnish and Standard Estonian ones. The treatment of Danish in the southern provinces (where most people anyway didn't speak Standard Danish but dialects grading into Swedish) was different because there was a quite real and repeatedly realized risk of the Danes trying to take region back.