Was there any conversation within the U.S government about using a nuclear weapon/weapons against Hitler during WW2. I’m just wondering how the war would of progressed if Japan didn’t attack Pearl Harbour? I understand that it may be (what if) territory.
In general, the concrete discussions about what to do with the bomb did not start until late 1944, with most of them happening in the spring of 1945. The only real discussion of this took place in December 1944, when FDR asked General Groves, head of the atomic bomb project, whether it might be possible to use them against Germany. The answer, for a few reasons, was no: it wouldn't be ready in time for use, since the US anticipated being done with Germany by May 1945, and wouldn't have a weapon ready until late July 1945. You can read more about this here.
As for what would have happened if Pearl Harbor never happened, who knows. That would be a very different trajectory (and involves asking whether the US would have entered into the war at all, and under what terms, etc.).