Working on a carrier board design for the Orin NX using the P3509-A01 design, which should be pin compatible with the Orin NX. But I see that the Orin NX SoM has different pin functionality for the SDMMC pins (#221, #223, #225, #227, #227) than Xavier NX has.
Jetson Orin NX & Jetson Orin Nano series modules are not pin-compatible with Jetson Xavier NX series modules, but you can design a carrier board for the I/Os they have in common, such that both modules are supported. Please refer to the comparison doc for detail. For Orin NX design, please follow Orin NX Design Guide in DLC.