In addition to automated testing of USB4 hosts, devices, hubs, passive cables, and active cable assemblies, QPHY-USB4-TX-RX provides multilane analysis, performing acquisition, analysis, and ...

He took this opportunity to reroute the chip’s TX and RX pins through the cable, which now gives him an avenue to use a UART-to-USB adapter without adding any cables to his target board.

USB is a high bandwidth, stateful, negotiating and identifying protocol. You're going to need at least a microcontroller, with suitable firmware: Which you may need to code.