Hi HuiW,
By default, the M.2 interface is not enabled.
To enable it on devkit, you (only) have to modify the “ODMDATA” to 0x90000 (by default, it should be 0x1090000) in p2771-0000.conf.common and re-flash your TX2.
You could refer to TX2 platform adaptation and bring up guide for this info.