Probably both. Divert pressure off the front. Disrupt supply lines and infrastructure (roads, bridges and railroads). I've also heard mention that one axis of advance is towards a nuclear plant.
I've seen some keyboard warriors theorize that the Ukrainians intend to capture the plant as a bargaining chip in negotiations with Russian because Russia currently holds a Ukrainian nuclear power plant. My (wild ass) guess is that if they make it to the plant, they will just destroy its ability to generate power, then retreat.
There is one big flaw with socialism: socialist governance seems to require concentrating an extraordinary amount of power in elite government decision makers; this tends to produce a new ruling class, the widespread deprivation of political rights for everyone else, and crippling poverty.