In the specs for the ASI183MM camera, different frames per second rates are given for both 10 bit ADC and 12 bit ADC. But it seems there is not a corresponding switch in Ekos, not under the streaming tab nor under the control tab.
What is more, using Python Imageio Pyav plugin, it appears that the data contained in the .ser file when streaming is saved contains only 8 bit data. Well, sort of. Each pixel is assigned 3 unsigned 8 bit integers, but since the ASI183MM is monochrome, those integers are all the same.
My understanding is that with cameras with bit depths like 10, 12, or 14 bit, they either scale the data up to 16 bits, or down to 8 bits depending on your preference. Many programs don't really have the ability to deal with those other bit depths. I am not sure, but I think the scaling is done either in ASI's driver or in the camera itself.