AN-124’s are extremely inefficient - it’s probably stopping 2-3 times on route, but still easier to arrange than flying each plane.

Both aircraft types will almost certainly be running Jet A1, or whatever the military version of it is.

pee before takeoff)

Iirc the factor that limited early nuclear submarines the most from continuous dives was the toilets, they have limited storage for sewage and it turns out that draining those with a greater outside pressure is a pretty difficult task, at least if you want to stay undetected.

Now that they have figured that out the limiting factor is food.

the F16 comes with neither legroom nor bathrooms.

But at maximum speed, it could in theory cover the 4500km in just over 2h (but probably with worse fuel economy and less range)

Sourly 6 hours flight time is not significant wear.

That, and 6x the flight hours for a F16 is expensive. The flight hours with accompanied wear and tear are better used over Ukraine.