Synopsys has just published a video on YouTube where they connect two bonded lanes over a standard Type-C cable. This was accomplished with a host USB 3.2 controller embodied by an FPGA board. The device controller is the same hardware that was configured to be seen by the pair as a USB device.
In case you're wondering, the demo happens at around 1:48. Blink and it's over.
From a practical standpoint, USB 3.2 is still some time away, and a factor of 2 speed-up is not too large considering the amount of bandwidth that USB 3.1 already provides. That said, more bandwidth is always better, especially when you’re running in industrial or other professional workloads, and especially in places where Thunderbolt has marketshare.