Hi @tveenker, thanks for your query. If you wish to use the Tobii 4C Tracker with the Pro SDK, this requires the purchase of a special unlock file and licence to do so, but yes in theory you could use the 4C as a “testing device” as any Pro SDK application should be compatible with the X3-120 assuming of course that the application itself does not depend on certain features unique to the X3 such as a high (120hz) capture rate.
Regarding emulators, I am afraid we do not produce any such software.