It seems pretty likely that Joyboy had the Nika Fruit, at least. And I do think it's possible that there are others who have had the Fruit over the centuries.
In fact, and this is probably going to sound like a weird idea, but I kind of have to wonder if a few of those potential users of the past are actually...other Luffys.
Personally, I'm kind of starting to wonder if the two prototypes for One Piece, Romance Dawn versions 1 and 2, could actually be canon to the main story of One Piece? I mean, we already know that Oda's old one-shot from Wanted, Monsters, where Ryuma first appeared is canon to the story. And most of the other stories in that collection could also take place in One Piece's World with pretty little consequences. It'd be pretty easy to say they all take place in the same world. I could see Oda doing something like that.
The exception with that is the two versions of Romance Dawn. But, with all this talk in the story about history repeating itself and the Sea Kings commenting on the "reincarnation" of Poseidon with Shirahoshi, I have to wonder if other characters are also being "reincarnated"? Could other versions of Luffy have existed in past lives, hundreds of years ago? Could one of these Romance Dawn Luffys have actually been the one who awakened the Ancient Giant Robot 200 years ago? I don't feel like it's impossible.
So, some other past users of the Nika Fruit could actually be the other two Romance Dawn Luffys. Maybe?