I finally found an adapter that you can buy off-the-shelf that will allow this to work via USB! This is the ONLY one I’ve found. If you look at the block diagram of it, found on the documentation on their website, it says that they connected a pull-up resistor to pin #20 (PCIE_DIS) which sets the pin to high (1.8V), enables the USB interface, and disables the PCIe interface.