x4 PCIe NVMe SSDs are faster than x2 PCIe types. The more NAND chips, the more paths and destinations the controller has to distribute and store data at.

PCIe Retimer and USB Retimer Market 2022-2028| USD 2578.71 million by 2028| CAGR of 47.74% | consumption by Regional data, Investigation and Growth, Demand by Regions, Types and Analysis of Key ...

The PCIe m.2 based SSD over USB 3.2 Type-C connectivity has been created to provide users with “superb speed and stability,” utilizing the Phison E13 PCIe controller.