An easy way to make upper boundary estimate: let’s say you use Falcon Heavy to deliver your kinetic weapon. Falcon Heavy burns around 500 tons of fuel. This is upper boundary for energy of your payload (since most of the energy goes to lifting rocket itself and air resistance). So even ultra-heavy payload of 64 tons will have way less then 0.5 kilotons of energy (TNT equivalent used for nukes). Any nuke is way beyond that.

Of course, another way to estimate is to not to be lazy and actually multiply mv^2/2. Truly massive 64 ton kinetic weapon reaching target at 7 km/s will have energy of 1.6x10^12 J. Modest 20 kiloton nuke has energy of 8.4x10^13 J. I.e. 50 times more.