Estonia is where the work was outsourced to initially.
Wiki says "Skype was founded in 2003 by Niklas Zennström, from Sweden, and Janus Friis, from Denmark.[26] The Skype software was created by Estonians Ahti Heinla, Priit Kasesalu, and Jaan Tallinn. The first public beta version was released on 29 August 2003."
Most of those are no where near billion dollar companies, and aren't based in Sweden either.
All of them was or are based in Sweden. After being bought by other companies some of them are no longer based in Sweden
Soundcloud is based in Berlin and hasn't ever produced a profit, much less had a 1b evaluation.
And I love Soundcloud, but what are you talking about?
King, Starbreeze, Paradox, Avalanche
Klarna
Yes, good one. Yubico is another HN folks should recognize. And then there are tons of game studios doing AAA games. Numerous network equipment vendors. And of course Erlang.