There are no need any HUB here if you just want to add a USB2.0 to high-speed ethernet chip. You can select any CCGx with Rp terminate chip, and then add a DR_SWAP in the firmware to present Data device role on Type-C port.
For example, CYPD3175, it is simple chip and can support various charging protocol.
This is not simple, I am not familiar with any of your development tools.
I bought the CY4532 kit to demo to see if I could make this work.
I have downloaded the basic programmer for the kit, and now find that I have to download your firmware environment and modify the code on the ARM core as shown in this thread. It would be simpler if you had some pre-compiled code for the more common applications.