This is a good question. As we all have known it, USB type C is capable of multiple outputs, even if it is HDMI, or Digital music, and of course Coax out is not out of the question.
It brings us back to a couple foundations of USB as an interface. It has to go through a processing chips. Let's take Thunderbolt IC chip for an example. The JHL 8540 is a chip for that, and it conducts universally for many different tasks. The question would be, was it made dedicated toward music ?
I am thinking that Hiby is also using USB type C interfaces but configured it to enable Coax out. This Coax out is already Digital to Digital Converted, and is not Pure Coax, as the signals have to go through the USB C processing chips and get processed before going out. This will define the Coax out to be yet another USB interface and not true coax. What would be worse is that it takes an "Extra step" to process. Everything Extra is not worth it
Though, I have not been following these new products lines up from brands like Hiby for example. You will need to ask
@Z_Showmaster and see what he knows as an insider ?