According to Jetson TX2 Product Design Guide, the RESET_OUT# pin should be held low by the carrier board, until the carrier board power rails settle to their final voltage levels.
But, there is a pull up resistor to VDD_1V8 on the Jetson TX2 module itself, pulling high that pin prior to the time that the VDD_5V0_IO_SYS power is applied to the last regulator on carrier board (APW8805 in P2597_C02 schematic. Also see Figure 7 and 8 in the Jetson TX2 Product Design Guide)
I think there is an inconsistency between two above points.
Yes, Power Good signal of the 1.8V regulator (APW8805) pulls the RESET_OUT# low, provided that it has a power supply!
The 1.8V regulator is supplied from VDD_5V0_IO_SYS, and this voltage is present after a time delay from CARRIER_PWR_ON.
See t6 in the Figure 8. At this time, the Jetson module 1.8V rail is present, pulling up the RESET_OUT# pin, and the CARRIER_PWR_ON has not been yet applied, and all supply rails on the carrier board are at zero volts.