I don't know if this has been touched on I haven't been keeping up with the discussions but I was catching up on the Boruto episodes and got to the Sarada Gaiden part where Shin came about and they went to talk to Orochimaru and it made me start thinking, Mistuki is a Shin(variant) Oro still had some of this Shin data as we saw in those tubes and we know he made other Mitsuki's. Oro mentioned Shin's body was perfect for incorporating new tissue, so I'm thinking Mitsuki is a Shin body with Oro tissue.