Here’s a Smithsonian article: https://www.smithsonianmag.com/smart-news/dna-analysis-reveals-vikings-surprising-genetic-diversity-180975865/

Here’s a different one, from… i dunno the site but this roughly reflects my understanding: https://scandinaviafacts.com/were-the-vikings-black/

I think generic testing is pretty suspect but at the same time we have more than just that to suggest this.

Remember, also, that the Vikings (like other people of their era) didn’t have an understanding of race in the sense we do today. Surely they had some concept of people having different skin color (they traveled enough) and of family lineage but the pseudoscientific idea of race theory has yet to be invented.

Anyway we can be pretty confident Viking slaves (thralls) were sometimes non-white and we know thralls could buy their freedom and free people could take up viking (the profession) so it stands to reason that there could be some. That plus old burial sites suggest that wasn’t just a theory but something that happened. i suspect the culture at the time was even more heterogenous than we would think just from that, though it seems like the white skinned types were still the majority considering modern Scandinavians.