Finland is Nordic but not Scandinavia. Because Norway is not an EU member, discussing a euro opt out doesn't make sense. Thus, OP is accurate in stating that Scandinavia got a Euro opt-out.
In Stockholm there is an IKEA in literally the most central and most expensive commercial real estate in Scandinavia -- at Sergelstorg. I'm moving into a new apartment now, so it has been extremely useful to have an IKEA by the central train station!