I know it's been mooted a few times but I don't know if there's a formal topic on this. I understand that the factory CM4 carrier boards route PCIe to the node specific PCIe controller (raw PCIe, SATA, USB, etc) for good reasons - cost, design history, usefulness etc. As I understand it, there are two alternative designs: routing it to the NVMe instead, or putting in a PCIe switch to allow both to be used (sharing bandwidth). What would it take to get such an alternative carrier board? Are the designs for the existing board available somewhere as a starting point? I am aware that there are careful considerations like keeping the PCIe traces the same length - what else would one have to consider if they were to try to design an alternative? Is it possible for a motivated technical amateur or do you really really need specialised design knowledge?

There is a possibility for an adapter board with either a a switch or differently routed PCIe lane. I don't know when, but even recently I mentioned this sot the Team seeing such high demand for it.