I’ve heard talk and speculation about that very idea, you have the speed and all you need is the mass and guidance.
Still, if you’re going to weaponize space it would be a lot cheaper to just build a stealth weapons platform with nukes than go through all that trouble, its not like you could do it quietly enough that the world wouldn’t know what you’re up to.
Kinetic energy penetrators don’t create radioactive fallout. Nukes don’t penetrate underground as well or as far as KE either.
With KE you can dial up what you need for TNT equivalent by using the right size projectile.
Nukes require regular maintenance or they fizzle.
Dropping rocks on their heads is way cheaper in the long run.