Most F/O's tend to focus outside when they are P/F as they know they are not responsible for an RTO.
They are also steering the thing, so focussing outside helps a lot...and they
are responsible for bringing to the captain's attention (if he's the PNF) anything they might run into, on the ground or in the air.
Shouldn't PNF be mainly focused on the temps and pressures checking for potential RTO criteria and calling it before V1?
Correct.