I had this idea before, looks like your testing around, I found that there were people doing this shipping with people traveling already, check this list out:

https://grabr.io/

https://www.piggybee.com/en/

https://www.manyship.com/

https://www.airfrov.com/

That would introduce some gratuitous thrill-seeking into my life. No thanks.

What am I going to tell the nice man at the border about what's in my luggage?

I think we call people who do this "mules".

how does it work?