I'm using an nRF52840 and SDK 15.2 (although I can go to hardware directly if required).
What I want to do is to set a pin as an output with a normal drive run high on it (the pullup isn't quite enough for me) and then read what is at the input pin (not what I'm telling it to drive). If something on the outside drives that line low, I want to see it.
Looking at the PS it isn't clear to me how to set this to both an input and an output...