This is pretty recent. The USB controller on the regular Pi 4 was sitting on the PCIE lines, so until the CM4 came out the only way to get to PCIE was to lose U

This is pretty recent. The USB controller on the regular Pi 4 was sitting on the PCIE lines, so until the CM4 came out the only way to get to PCIE was to lose USB support and solder wires onto the traces on the PCB. A couple people did it but not many. Most people could get by with a USB 3.0 accessory and didn’t need to cut up their Pi. But now that the CM4 has a PCIE slot on the daughterboard it makes sense to see what is compatible.