Sony registered a new fixed camera the WW 151602 which is most likely an RX camera due to the Sony NP-BJ1 inside.
Nokishita update:
It was rumored that Sony will announce one model of the RX 0 series and at least another mirror type in the first half of 2019, so this time it was registered as a new model of the RX 0 series.
via Nokishita