Did Putin fancy himself as reuniting Russia and USSR to the glory days he thinks they deserved, absolutely. But he also felt he was going to have a 3 day excursion where they would do what they had done before in Georgia, Crimea etc.
And of course they spoke Russian, as they had been taken over for 50 years by USSR and forced to teach and use Russian as the primary language
But Ukraine was wanting to be it’s own country, and if Ukraine could access and leverage their oil reserves it would make Russia less powerful and influential, and even superfluous to Europe or other countries. Putin and the Oligarchs are state sponsored Mafia, and a Ukraine that could compete or supplant Russian oil/gas could be economically and politically devastating.
So Putin could work to diversify his industries, become better economically overall, be a better global partner….or he could make up Nazi, bio-warfare, nuclear, NATO, etc issues and do what he has always done as the head Russian Mafioso.