I do not believe that Dragon has *that* devil fruit actually
The latest chapter introduces the character/idea/myth/legend of the rain Goddess ( whatever the "Gods" of one piece really are). Some people have started to theorise that it is the devil fruit of Dragon. It fits very well. We have seen him associated with the rain, the wind and even lightning. The idea of the Celestial Dragon being scared of rain round up everything thematically, what with Dragon being their archnemesis.( You might even be more convinced if you have watched Mr. Morj last two video on the gods fruits and the man marked by flame) So, problem solved ?
Well, I am not convinced. Elbaf reinforced a concept that we were already aware of. The Nika fruit evaded the world government for centuries and followed people similar to Joyboy until it hit the jackpot with Luffy who was able to awaken it. Chopper "human human fruit" was said to be useless ( ? ) if a human ate it. And in Elbaf, we learned of the Niddhog fruit who only reveals it's true might in the hand of an ancient giant. Point is, some devil fruits need to be in the hand of certain individuals with precise characteristics to reveal their full might.
You have probably guessed where I am going with this : I believe the rain Goddess Devil fruit, if it exists, would naturally only reveal it's full power in the hands of a woman ( or at least a queer character like an Okama ? Who knows, probably the Goddess doesn't discriminate) And there is a serious candidate for that power in the endgame : Vivi.
She has a thematic connection with the rain, both her and her ancestors are enemies of the Celestial Dragon, her lineage and Character are set to be VERY important in the final saga, and she is an honorary Strawhat. For me, she is a much better fit for that power.