I doubt Russia's nukes still work. They would create a localized environmental atrocity where they landed, but that's about it.

It costs a king's ransom to maintain a nuclear arsenal, as Ukraine well understood when they made the decision to give their own weapons up. The people charged with maintaining Russia's nuclear weapons since the fall of the USSR had absolutely no incentive to do anything but divert the funds for their own purposes. That's just how the Russians roll.

Meanwhile, ours will most likely work as intended. The question is, does Putin feel lucky? Well, does he? (Don't answer that, please -- I don't actually want to know.)