I think it would only be cool if Rocks has his own spin to it. Like if instead of seeing it as a “medical fruit” he sees it as the perfect assassination fruit. Otherwise it would be a waste to give the same fruit to 2 characters.
I do really like the technical use to transfer his body into teach. Another possibility is that he made teach immortal, which is why he can eat multiple fruits. If he survived Gods Valley and managed to find his way back to Teach’s home he could’ve used his last days to give his kid the ultimate ability and for him to follow his will
Ultimately I don’t see it happening because I think he like Teach was looking for the Yami Yami no mi, and unless he can also eat multiple DFs it wouldn’t make much sense for him to do so.
One thing to point out is that if he has a fruit, it is one that let him escape Marejois with very little trouble. So while the OP OP no mi is a possible candidate, there’s probably plenty of fruits that could also fit this