Yes, there was a third option - blockade.
In fact, Curtis LeMay in “Mission with LeMay” says it “might” have been possible to starve Japan into submission with a blockade.
But it would have killed tens of millions of Japanese, mostly the women/children/elderly civilians the the no-nukes dreamers get their panties most in a twist over.
I’m not one of those folks who believes that dropping an atomic bomb wasn’t justified by the total war Japan had waged on the Allies. Arguing it was a ‘necessary evil’, implies two things that just aren’t so. One, it wasn’t necessary, and two, it wasn’t an evil. All the alternatives lead to higher casulties on both the American and Japanese side.