@FillyofDelphi
No need to think about the swedish-finish landborder. Ever looked up
the Âland Islands ?
Aside being an ... asset of longstanding swedish like-to-have, esp. early in 1914 they were only veery lightly fortified :
ideal region for an "island-hopping" towards southern Finland and from there relativly easy - given a not too unfriendly population (

), possibly fed up with russian rule - towards helsinki and further.
For the then somewhere in late(er) 1914 or better early 1915 I could well see the swedes advance towards St.Petersburg, with the russians just not having enough forces to spread everywhere, esp. to another, to the others completly unrelated theatre-of-war.
However. What would be of more interest for me :
Was there a kind of "nationalistic grouping" in Sweden, that would have supported a war against Russia ? ... for nationalistic gains ?
And if so :
how "strong" actually was such a kind of pro-war-faction/movement ?