While I could see her having a DF, I would vouch for a pure dragon/oni shapeshifting breed and naturally Kaido would follow with that assumption. Three reasons why I think this to be the case-
- This would open up possibilities of us getting whatever was going on with Vegapunk's experimentation with dragons, research on ancient giants of which Kaido and Yamato look miniature versions. Momo's artificial devil fruit being a part of Kaido's lineage factor etc.
- Kaido being called the strongest creature in land, sea and air
- The fact that Yamato had the same handcuffs for 20 years which Luffy broke without even slightly getting weakened means that they weren't made of seastone. Seastone originates in Wano and if Kaido had to restrain a DF user he would obviously use sea prism cuffs.