Hi Catherine, welcome to the forum. I’ve heard some of this speculation, too. As far as I know Kinefinity has never confirmed this – most manufacturers neglect to name which off-the-shelf products they use – but people have been pretty clever about comparing resolutions and frame-rates to make guesses about which cameras use which sensors. I’m not familiar with the specs of the A73 but if they share the same frame-rates etc, then there’s a good chance they use the same sensor.
It’s important to remember that a camera is more than just a sensor, though, and that, for instance, the Mavo LF can record in ProRes where the Sony cameras tend to record in a more highly-compressed codec.
Let me know if you figure out whether it matches, though.