Even limited use of nukes would be horrible. There will be so much more suffering if the breadbasket of Europe is reduced to an irradiated hellhole thanks to Putin’s delusions of grandeur.
they need ukraine to be usable for annexation so expect at most kyiv and maybe 1 or 2 other cities to be lightly irradiated.
like after a few months it would be cleaned up.
the real damage is to the people who would be in the areas, they could have generational dna damage.
Irradiated rubble anyway.
Contaminating the Ukraine will equally contaminate Russia. Moscow will not care, because Moscow will not be affected. But they are already preparing for the outrage of such stupidity.
The use of small yield tactical weapons would almost certainly escalate to full blown nuclear exchanges, it's a pandoras box that won't be closed.