I doubt it's a Kamidogu. It's probably just some trinket or something.

isn't that Shinnok/Quan Chi's medallion?

No, the corner's of the thing in her hand are sharp, Quan Chi's medallion is a complete circle.

Did anybody find any more info about this? Of all the games to produce new details over time, I wouldn't have expected MKvsDC to be it. Then again, with so little content to be accessed, maybe that just means it's even more likely there are some nuggets hidden deep inside the disc.

Or it's just a fake.

Isn't that just that jeweled thingy she steals in Gotham in an early chapter of story mode? Flash tries to catch her, and then Kano shows up, etc.