The Ukrainians appear to be in some trouble at the moment. I was expecting the Russians to make progress in the cauldron, but not around Kharkiv. Although I'm not sure the extent of the gains there.
The Ukrainians have a few hundred thousands soldiers who are training to be ready towards the end of August. But they are also down a lot of their best experienced soldiers either dead or they have to have time to rest as well. They also need a lot of those experienced soldiers for training all the new conscripts.
Another huge problem for the Ukrainians is they are basically out of their Soviet era ammo for their artillery and possibly their Soviet rocket trucks. Even though they have some Western equipment and ammo, an army also needs a lot of 'bulk', like many positions with just regular Soviet artillery, tanks, guys in trenches, etc.
Its like the US rocket trucks.. when added to a large regular army they are badass. But on their own they just have to retreat.
It has taken forever but the US and NATO countries are finally pulling a bunch of old retired artillery out of storage and getting it shipped over there. But that process is just beginning it will take time to scale up. Plus the Ukrainians need a huge amount of the NATO artillery shells for those. There is also old NATO tanks and I am guessing other military vehicles the Ukrainians could use.
In war both sides are also learning. For example the Russians got beyond rocked at the start, but they adapted to this WWI trench warfare and artillery style. And then presumably they are finding what is working with that strategy so getting better and faster.