Yes, you are quite correct. The infrastructure that is in place barely survived a virus. Even if the weapons were all detonated in Eastern Europe, the effects would be realized worldwide.
Covid and the mismanagement of Covid killed about 1 million people and severely damaged the economy. It was about the equivalent of one mid-sized city getting nuked.
A limited Nuclear war would be about 20-50 times worse.
A full-scale Nuclear war would destroy Western Civilization and Russia. What is worth that?