You might have seen x16 to four NVMe slot cards online – invariably, somewhere in the corner of the card ... PCIe host interfaces for all your devices; you could compare them to Ethernet ...

This showed that the Raspberry Pi would happily talk with a VL805-based USB 3.0 PCIe expansion card, as well as a Realtek RTL8111-based Ethernet card ... have both PCIe x1 and USB on a Raspberry ...