Its Christmas, give it time. Have the seller ping USPS to trace the package if it has been a while.
When I was sewing I shipped alot of packages USPS over the years and I think once they lost something into the ether and that was it, luckily it was something I made so I could just make a replacement and send it out.
My biggest eyeroll was I shipped something to the address a buyer provided me, turns out they gave me the wrong address, it was a real address and the package was delivered to it but it wasn't their address. The buyer felt it was up to me to replace the items and pay shipping again because they didn't receive what they bought despite it being delivered to the address they provided. As a cost of doing business I did it but didn't think very highly of the person putting their mistake onto me.
When I was sewing I shipped alot of packages USPS over the years and I think once they lost something into the ether and that was it, luckily it was something I made so I could just make a replacement and send it out.
My biggest eyeroll was I shipped something to the address a buyer provided me, turns out they gave me the wrong address, it was a real address and the package was delivered to it but it wasn't their address. The buyer felt it was up to me to replace the items and pay shipping again because they didn't receive what they bought despite it being delivered to the address they provided. As a cost of doing business I did it but didn't think very highly of the person putting their mistake onto me.