this will cause Russia to have to spread troops thinner
Yes, I think this is a very crucial point, Russia has pretty much been able to control which points are hot spots, so they could concentrate forces there.
But now Ukraine has been able to push through, because they chose a poorly defended area into Russia, instead of trying to push Russians back on the front lines in Ukraine.
They have made an offensive that wasn’t costly, but they can still make costly for Russia to take back. So now part of the war is on Russian ground, and destroying Russia instead of Ukraine. Literally taking the war to Russia.