100,000 North Koreans!
Russia needs 100,000 North Korean soldiers. Use them in "back end" roles, mainly managing the border and engaging the enemy from there. Kursk veterans would come in handy to train them.
I would even go as far as cucktin, deploying them only in old Russia borders so in that way the esteemed western partners could not complain about evil norks in ukranda
This way the majority of Russia's soldiers could focus on taking the rest of the 4 oblasts, maybe even venturing west towards Odessa