If he is completely deranged and wants to start a nuclear war he could’ve done so without sacrificing so many Russian troops.
He can sit in his bunker and order a nuclear strike and even if most forces would disregard that order it only takes one launch to bring on the end of the world as we know it.
He knows he is running out of time and he wanted a new Russian empire to be his legacy but I don’t think turning Europe and North America into glass is on his todo list.
At least I hope not.