We know that Punk Hazard was originally a place for the World Government to experiment and torture pirates who were captured secretly.
We also know that when Kaido was first formally introduced, it was specifically stated that he was captured by his Enemies and the Navy 18 times.
Although it did not specifically mention what enemies, it mentioned that the World Government captured him at one point. Furthermore, we know that Vegapunk at one point was in Punk Hazard and created the artificial dragon fruit using lineage factor, which is another term for DNA.
Based on the recent chapters, we know that Kaido has eaten a Mythical Zoan-type Devil Fruit that allows him to turn into an eastern dragon. I’m assuming that Vegapunk had to have a source for a dragon-like organism’s DNA, so Kaido was that source.
We also know that Momonosuke’s artificial devil fruit and Kaido’s dragon form are incredibly similar. Too similar as they both resemble an eastern dragon.
It would make sense that if Vegapunk had experimented on Kaido, he would be able to create a devil fruit completely similar to his dragon form. The reason why Orochi wanted Vegapunk in Wano was not because of himself but because of Kaido. Kaido is well aware of his capabilities of creating powerful zoan devil fruits since he was experimented on.
*Theory by LordOfTheBoxes
