This whole idea is dead on arrival because of this.
Most nations actively warn their citizens never to carry packages from someone you don't know, and never to carry packages you didn't pack (or saw opened) yourself even for people you do know. And still people agree to carry sealed packages for someone they had a few nice nights with on holiday before boarding the plane back home. That tends to end in a little room on the same airport with security/police grilling you before sending you on to the judicial system where the tough-on-drugs judge will sentence you to a couple of years of extra holiday. In a cell with rats.
There is no way to clear this legally and ethically.
Even across state lines is a big risk but carrying unknown packages into another country is astronomically stupid. You don’t get to play the “I didn’t realize” card, either, when you lie to a customs agent and claim you didn’t accept packages from anyone else.
Even just going to the Apple Store when you're in NYC for someone and bringing back a brand new Mac can get customs officials interested.
I'd be hesitant taking anything from anyone, even a child handing a letter to be postmarked in Florida.