I've met quite a few people with exotic herpetiles personally through the Chicago Herpetological Society. I know of at least one member who owns a juvie anaconda, a few who own crocodilians, a few with rare monitors, etc. And afaik these are all owned legally, with proper documentation if needed.
I'm also aware of several exotic mammal pets like lemurs, monkeys, sloths, exotic hoofstock...they sometimes show up dead of natural causes in the Oddities Community. I think the most exotic I've seen that came from private owners were mandrills, sloths, and a red ruffed lemur (although the page that was processing the lemur was -rightfully- nuked for violating Instagram guidelines because the page owner was attempting to sell it. This would have potentially violated the Endangered Species Act.) I actually know of quite a few people who got educational osteological specimens from private zoos.