Slavery violates the NAP so IDK how an ancap would argue human trafficking is acceptable.
Selling, renting, or enslaving ones child can, in a certain system, not only not violate the NAP it can all be done "legaly". Slavery violating the NAP inherits a huge host of assumptions about morality and self- or mutual interest, that are derived from religious and non-anarchic civilizations. Nothing about the covid saga inspires me to believe for an instant this species is mature enough to behave without a strong hand. Good luck if you do, i don't see the evidence.