Buy the lowest miles 5th gen 4 Runner with the rear locker and the KDSS (Toyota’s sort of sway har disconnect). Still made in Japan, up to Aug ‘24, I believe.
The 4.0 V6 is one of, if not the best, engine’s Toyota ever made. I‘ve driven 3 of them (2 Tacomas and my wife’s current ‘18 4 Runner) a LOT in remote places and a lot of miles and never worried and never had to do anything other than routine maintenance.
Take out the rear seat bottoms (4 bolts, 5 minutes) and your dogs will love it and you’ll have tons of room and capability. A mild lift, tires, and shocks and you can rock crawl more than enough.