what is the longest theoretically possible domestic flight accounting for max range of current aircraft and runway length

any country

it's 50 miles outside the range of the furthest flying airbus unfortunately

Super convenient for Air Tahiti Nui that its current LAX stopover is right on the great circle route

PPT-RUN is a bit shorter if you want something that doesn't require a nearly-empty aircraft

oh man this is a weird route

apparently commercial flights from auckland to santiago sometimes graze the antarctic coast

Still boggles my mind how few regular transoceanic routes are exclusively in the southern hemisphere