Hi,
From AGX ORIN Pin Description file, for most of the Open-Drain GPIO pins, it is given as “Open-Drain, 1.8V (3.3V tolerant, back-drive capable to 1.8V)”.
From this, I understood that these pins do not require 1.8V Pull-up resistors externally. But they require pull-up resistor when 3.3V is used.
In short, 1.8V works like normal Push-Pull pins and when 3.3V is used it works like Open Drain.
No. Are you using these pins for OD function or GPIO function? Pull-up is must only for OD usage. For those pins without pull-up on module, you can use it as GPIO or OD (adding external pull-up on carrier). Anyway, you should check the Orin pinmux sheet in DLC for usage of each pin.