Ah, so it isn't about Nazis you mean, it's just good old fashion conquest, 19th century style. Glad you've finally admitted that.
Taking Kiev was to force a surrender/aim for regime change/distract UAF... Not conquer.
Denazification, demilitarisation and taking away Russian speaking zones, ie, the south and Donbas, including Odessa, that's always been the objective.
The Russian speaking zones stretch from Kharkiv to Odessa.
So, for Ukraine, all the dark blue areas are the enemy.
A long term objective for Russia is to unify all the Russian-speaking areas in Europe. So, if the Russians succeed in Ukraine, there may even be a population exchange program.
Novorossiya:
Novorossiya will be an independent country and act as a buffer. Which means any NATO invasion on Russia will require becoming an aggressor when going through neutral buffer states. Plus, with the region largely supporting Russia, there's unlikely to be any major fear of an insurgency.
Taking Kharkiv means the front will reduce to just 450Km instead of 1300Km. It also cuts off NATO access to the Caucasus from the north. Crimea does the same from the west. And from the south, through Georgia, the mountains will make an invasion difficult. And, on top of that, the 450Km front along Ukraine will be difficult to man because Belarus and Dnipro puts Russian forces behind Chernihiv and Sumy, which means any NATO forces there can be encircled, making it unviable. To top that off, the Russians are pretty strong opposite Chernihiv and Sumy at Kursk and Bryansk.
They are not conquering anything, they are finding new ways to protect themselves better.