Hi,
Thank you for your interest in NXP Semiconductor products,
The RESET CONDITION is after POR_B rises.
During reset condition, we couldn't manage the GPIOs nor the status of them. The reset condition assigns a default function to every pin after POR_B rises, so BootROM is executed correctly and the boot pins are ready to be sampled.
This condition means that boot modules are initialized at BootROM level, GPIO wouldn't but USDHC, NAND, FlexSPI, USB, etc.
Regards