The conduct you ascribe to Rommel is not “standing up” to Hitler. Standing up to Hitler meant meeting him face to face and disagreeing with him. Rommel never did that.
What you describe was mere insubordination, even if properly motivated for humanitarian reasons.
Rommel got into it face to face with Hitler in 1944, in France. Twice. Once with Rundstedt, and once without. On both occasions, Hitler was told the war in the West was lost, and had a strong suggestion directed at him that he make peace.
That was a lot more than Guderian ever did. His blowups with Hitler were over the perceived impugning, by Hitler, of the Army’s honor. Coming from a man who served on the honor court that threw officers out of the German Army so they could be delivered to the Gestapo after 20 July, that’s a bit rich.
I can find no instance where Guderian urged Hitler to end the war, or told him it was lost.