Let me give some armchair analytics about "overwhelming support". In the beginning Putin promised that there will be no mobilization, yet later he mobilized an unknown amount of people. Also, he passed the laws allowing to recruit convicts from prisons and people under investigation (they are sent to most dangerous and deadly missions, often without proper cover and evacuation). Also the government raised a reward for signing a contract from somewhere around $4 500 to $20 000, and the recruitment posters are literally on every bus stop. All of this means only one thing - there is not enough volunteers.
So if you make a street interview maybe most of the people will express their wholehearted support for special operation (especially given that expressing disagreement might put you in trouble), and maybe they will even give you strong arguments why it was inevitable and justified. After all, over 80% of voters voted for Putin. But why those 80% do not want to join the military and help their brothers and support their leader in the frontline?
But on the other hand, there are no significant protests against the war. There were some protests in the first days, but they were not numerous and after approximately 15,000 people were arrested, they stopped.
So while there might be many people expressing the support for the war, they prefer to support it from the safe distance. War is necessary but can we please send someone else there?