Using OIKWAN usb-c to ethernet cable on catalina I bought this cable
https://www.amazon.com/USB-C-Cisco-Console-Cable-Windows/dp/B0774JV2QQ
and installed FTDI drivers
and the system profiler does pick it up:
FT232R USB UART:

  Product ID:   0x6001
  Vendor ID:    0x0403  (Future Technology Devices International Limited)
  Version:  6.00
  Serial Number:    A91UIYBK
  Speed:    Up to 12 Mb/s
  Manufacturer: FTDI
  Location ID:  0x14400000 / 1
  Current Available (mA):   500
  Current Required (mA):    90
  Extra Operating Current (mA): 0


and i even turned on the kext
 kextstat| grep FTDI
  154    0 0xffffff7f84653000 0x7000     0x7000     com.FTDI.driver.FTDIUSBSerialDriver (2.4.4) B137605C-32D8-3E81-89B6-E1F8039FC427 &lt;88 64 6 5 3 1&gt;%   

but when I have the cable connected from the macbook to the router, no USB connection for internet comes up in the network profile under system network preferences.
Not sure what else to do
You’re not going to find it in Networking, because it’s a Cisco console cable and USB to RS-232 UART all-in-one.   The Cisco console cable is a serial cable, with a DB-9 on one end and an RJ-45 connector on the other - it’s not Ethernet.
You will need an application like screen (comes with macOS), Minicom or iTterm2  that allows you to connect to the serial console.  Most importantly, when you plug it into the router, you cannot plug it into any of the network ports - you need to plug it into the console port.