I assume the POD is the Russian Empire keeping Alaska? Hmm. I'll first admit I'm a fair bit ignorant here, so I'm just positing. What if Russia manages to detect the valuable materials in Alaska that America ended up finding out was there, and therefore Russia didn't sell it, thus leading to migration into Russian Alaska from the motherland creating a nicely sized settlement in the region. Have Russian Alaska, like the American colonies in relation to the British, become a place freer from Imperial oversight leading to a sense of liberty among the population. Have Communism as an idea blossom in Russian Alaska, bolstered by increased Imperial repression in order to bring more direct and authoritarian control over the region. Russian America declares its independence.
Whether that has any feasibility, I have no idea, so feel free to pick it apart.