Like carve out a place between Russia, Belarus and Ukraine in the former Pale of Settlement. Establish a bunch of Yiddish language schools there. Have it become a center of Jewish culture. Sure, there are already Ukrainians, Russians and Belorussians there but there were already people in the far east too.
Giving Jews a place where they could be fairly autonomous within the union while not having the authority to create an ethnostate would be pretty dope, but the location of the Oblast was very silly. They could have had a Jewish SSR within regions that already had a significant Jewish population.