Therein lies the problem with MAD.
Once someone is arrogant and stupid enough to detonate one, the rest of the world will not be far behind.
Use them or lose them.
I expect NK to become extremely stupid if the balloon goes up.
Pakistan and India will likely annihilate each other.
Who knows what Iran will attempt to do to Israel.
I’m not aware of any war gaming that ended with only a limited exchange, but I suppose it’s possible.
The country who sets the first one off will be the least expected to do so.