Russia probably does want all the territory it had at some great empire expansion, what country doesn't want the maximum borders? What it thinks it can geopolitically GET though, is more a matter of security. The European plains are wide and open, and all of their borders are just lines on agreed paper. The Dnieper River is a natural boundary like the Black Sea and the Caucasus Mountains, it also isn't extending past Moscow Latitudally. Ukraine was never allowed to join NATO because of that border, but the Dnieper is easier to protect from land invasion. Close the bridges and there's little access you can't make yourself.

Of course, that border is easier to have when it's not AT Kyiv's doorstep, so more likely the Cherasky and Kyiv Oblast would stay in Ukraine's hands as well. That still better follow that Latitudal divide emerging along the Finnish and Baltic NATO borders. Belarus (and maybe a purchased County trade from South Lithuania in exchange for economic support to the Baltics to connect Kalinigrad) could either be an ally state or taken over in the wake of a collapse so both NATO and Russia have a territorial foothold on either site of the big LINE which would provide a new Concert to hold for however many years ahead as the EU states confederate and eventually unify as smaller states create military blocs to hold in the multipolar world.

Then NATO can close access to the Atlantic as a punishment, forcing Russia to play nice for that international trade while also ensuring NATO doesn't have the logistical access to just roll up to Moscow.