Umm as for PIA B777s I am 99% sure they can fly nonstop from WA
to Pakistan with full load of fuel and few pax and/or cargo.
ATRs? They just have lots of stops enroute, just like a milk run
A32Xs or B737NGs? Umm they umm have >5000kms of range how far do you think they can fly with full fuel and no pax?
Just an example of deliveries of our 3 A332s earlier this year, they all flew YUL
(Montreal - Kuala Lumpur (Subang)) non stop with full load of fuel. IIRC it was more than 14000kms and took about 16 hrs to arrive. Upon touch down they still had enuff (well sorta) fuel for a diversion to airports 50 minutes away.
I don't think ETOPS restrictions apply for such delivery flights, more of a one-off scenario.