The information you have found in the documentation i would assume is the most accurate, unfortunately, the information Melvin provided i have not been able to find as ad Melvin is no longer with Amcrest i am unable to request his sources.
The letter at the end of the model number is the color of the device.
information on the chipset can be found outside of our support very easily, I found the following info for the IMX290 Sensor. https://en.ids-imaging.com/sony-imx290.html