Lit –
“1) The population (Jewish and general) and land area of of modern Lithuania is a lot smaller than that of Poland, where Hasidism was more dominant.”
Are you trying to say that there were less Litvish Yidden that Chasidish and Oberlander Yidden in the prewar period?
Jewish “Lita” refers to more than just modern Lithuania.
“2) Oberlander are like Litvaks in that they both rejected the new Hasidic movement and stuck to old fashioned Yiddishkeit.”
Oberland, i.e. the Chasam Sofer, etc., did not reject Chasidim. They were on very friendly terms and interactions with them even though they never joined the movement.
And after the war large segments of Oberlander Yidden (i.e. Vien, Dushinsky, etc.) joined the Chasidic movement.