Nobel created his prize because everyone knew him for creating bombs and he wanted to be remembered for doing something good. Awarding someone a Nobel prize for creating a giant bomb would be pretty ironic.
To be fair, had he lived longer then he would have received a Nobel prize for his work in astro physics in relation to gravitational collapse. This work would later become far more important than his other work as his contributions would lead to the discovery of black holes
Fun fact: Alfred Nobel was the inventor of dynamite, and prior to establishing the Nobel Prize, it's what he was primarily known for. It was an explosive that became infamous for its use in war at the time, there was even a French paper that wrote "the merchant of death is dead" to announce the death of his brother whom they had mistaken for him. Though noone knows exactly why he created the prize, some people think he did it because he didn't want to remember as "that guy who invented the bomb". If that's true, then he succeeded, because nowadays most people know him as "the Nobel Prize guy"
So it would actually be extremely fitting if Oppenheimer won the prize for the atomic bomb. And if Nobel did in fact start the prize in order to rewrite his legacy, then it would still be pretty ironic, just for a different reason.
Oppenheimer never won the nobel prize. He was nominated numerous times, but never won.
