Jolla opened and reflashed all the phones that were in the first and probably also in the second production batch. We don't know what was the original OS that was installed in the phones. Was it Android, some developer version of Sailfish OS or a diagnostics OS. The factory needs to test devices before packing them and it might be different than what is in the device when it is delivered to the end customers. It might also be that the factory has automated some parts of the testing so it might require some specific OS that is different from what is the final OS.

The same goes for the tablet. We don't know what image the factory used for the tablets originally. I wouldn't be surprised if the factory actually installed Android on them and then Jolla reflashed delivered ones at Hong Kong before sending them to customers.