I've hunted with various caliber handguns for 5 decades,
lots of you guys may have more experience, or different experiences, but don't for a minute think a handgun in the hands of an experienced hunter is not rapidly lethal.
in most case revolvers like my 8.375" barrel, 357 mag revolvers, 10" 44 mag, a 1006 semi 10mm, 10" 445 DWSM and and a 7.5" 500 S&W
and the one thing you notice very rapidly is that its precise shot placement, not just power level alone,
and a rather heavy for caliber bullet, pushed to near max safe velocity for the handgun you select,
that provides deep penetration that maters.
yes a 44 mag and larger calibers do provide noticeably more impressive results, on initial impact than a 10mm or a 357 mag,
but all handguns are lethal if you shoot well.
you can shoot large hogs, deer, and even ELK in the heart/lung area and they tend too run ,
even with a 100% lethal hit, the elk I killed with a 44 mag, ran about 40 feet, stopped looked confused and after about 30 seconds fell over,
bullet destroyed all the arteries over the heart and cut lots of shoulder muscle on one side
.I try hard to punch through the shoulder into the spine , with a bullet that punches through and exits ,
after breaking all the bone and cutting vital nerves/blood supply etc.
and the animals tend to drop where they are hit.
your going to have extremely limited time, and ranges will be very short in a defensive handgun confrontation
so shot or magazine capacity is in my opinion not a huge factor, you'll be lucky to get off more than 1-2 shots.
Ive been charged once by a large hog,
I used a model 29 44 mag with 300 grain hard cast bullets,
I could not even see the hog in the tall grass until he was about 20 ft away,
I had maybe 2 seconds to respond,
but I could see the saw grass parting like the wake of a boat as he charged,
I remember firing once, but there were two bullet strikes and two empty cases in the cylinder,
one hit the shoulder and exited lower in the opposite side ribs, one shot hit between the shoulders and exited lower rear between the rear hams.
I had fired both shots double action at under 10 feet.