Sigma CEO Yamaki said in a Dpreview interview:
We’re still at the research and development stage for the sensor. It’s mainly being worked on by Sigma engineers here. It will take some time to have a prototype of the new 3-layer X3 sensor and then we’ll see if we can move to the next stage, which will be a product. I don’t think we’ll have a product to show in 2021. Maybe 2022 or even 2023. We don’t know what kind of technical issues or challenges we’ll have to solve with the sensor yet.
Sounds like we have to wait a very long time to get this :(