Prevent GPIO change in bootloader

My custom nRF52840 board uses the STmicro STM6601 push-button controller. To keep the nRF powered, the PSHOLD line must be kept high. I have a GPIO set as an output for that.

I am trying to incorporate the Open bootloader in my code.

Obviously using a reset (hard or soft) will change that GPIO to an input, causing the PSHOLD line to go low.

I can successfully call the boot loader directly without a reset, but it seems to reset the GPIO pin to an input anyway.

I would like a suggestion on how to keep that GPIO set through the bootloader initialization.

Where in the Open bootloader process does it reset the GPIOs?