As far as all the sources I can find say, 'hone in' originated as an error for 'home in', but has become widespread enough to be considered an acceptable varian

As far as all the sources I can find say, 'hone in' originated as an error for 'home in', but has become widespread enough to be considered an acceptable variant. If one of them is being let in erroneously by the nasty descriptivists at Merriam-Webster, it'd be 'hone in'. But either one gets the meaning across, so I don't see the issue.