I like Nukemap, however the problem is that there is no way to have multiple target sites.

Having a visualization of one target site is useful but if it was a full nuclear strike lots of targets would be hit by smaller yielded weapons (I am not an expert).

Industry, Military Bases, Infrastructure and Communications

AFAIK population centers are secondary targets in a first strike, however in a MAD (mutually assured destruction scenario) everything would be a target, right?

example targets for UK

https://i.dailymail.co.uk/i/pix/2014/06/06/article-2650518-1...