Haven't seen such reset output signal we may had in previous architectures. ONOFF can generate reset but is an input. PMIC-ON-REQ is a wake up request after ON OFF has been pushed but only if you use this optional scenario. The real reset signal is POR/. Even if it is asserted by PMIC once voltages are stables, you can use the same if the intent is to propagate it to your peripherals.
To manage further cold or warm resets, you need to analyse the possible sources in your system (check SRCF_SRSR for the list) to disable or combine them :
* Warm reset : software reset, can be disabled or obviously managed by software
* Jtag : you can use same external signal if hardware, probably avoid software jtag reset
* Watchdog : WDOG_B signals can be configured as output
* Ipp_user : ON OFF button if used
* Csu : if security / tamper is enabled
* Ipp : POR/ pin
Best regards, Philippe.