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.
Koenigsberg/Kaliningrad. They deported all the Germans from there as it is but just moved regular Russians in
Yeah that's what I meant by East Prussia