Back in August Chiappa posted a video to YouTube that says:
The new Rhino 9mm / .357 combo and .40 S&W are here! Available in 2", 4", 5" & 6" barrel lengths (Availability may be limited in some barrel lengths) Contact your dealer today!
So that sounds like the 9mm is not a separate gun, but just a cylinder conversion for a 357 Rhino.
They also said "contact your dealer today!" And that was back in August...