No close air support so Ukraine have to concentrate on eliminating the Russian logistics and artillery. Compare these two:
Cluster munition will compensate CAS somewhat as it can clear mine fields and Russian positions.
An interesting suggestion I saw says the Ukrainians can open the cluster shells and send the individual bomblets via drone to drop directly into occupied trenches or on top of tanks carrying infantry riding on top. I have seen several impressive videos where drones have dropped grenades on a small group of roving Russians and killed 8 or ten with 2 grenades. On the other hand the whole bombs would be useful if Russian tanks were moving across open fields with infantry riding on top of the tanks. THe bomblets can disperse widely causing havock among the infantry.