Apart from a few strikes on key locations, they haven’t pushed on into west Ukraine. They are making a shambles of it. Poland is nato. If they can’t beat Ukraine then they can’t do anything conventional to nato. The whole ‘he won’t stop at Ukraine’ thing is nonsense (it has to be for everyone’s sake).
He won't want to stop, if you're a former USSR non Nato member he has plans for you. Putin once said, "The breakup of the Soviet Union was the greatest geopolitical tragedy of the 20th century."
That's what he's been working on for decades.