Are there any NXP or third-party development boards that feature a Layerscape processor such as the LS1021A as a PCIe Endpoint? All of the NXP development boards focus on the LS processors as PCIe RC.
There is this note here on modifying the LS1046A-RDB board so that mPCIe Slot 2 can be converted from RC to EP mode:
https://community.nxp.com/t5/QorIQ-Knowledge-Base/LS1046A-RDB-in-PCIe-Endpoint-Mode/ta-p/1107415
But even with that change, you would be left with a female mPCIe Slot on the board. I could not find an adapter that would allow you to connect that mPCIe Slot to a PCIe x1 connector on a desktop PC.
If we wanted to debug a PCIe driver to a Layerscape processor, it would be better to do so on a development board before performing a custom design.