I feel there may be some confusing information here.
If you are sending 50 Cartons from China to Amazon, you can ABSOLUTELY just use LTL as the option (no need for pallets), and Freight Forwarders can sort how it is packed and sent into Amazon.
I use Lian Hang Da from the Resources. I have used them for 7 years and never had to ask “how does it get sent in?”
I literally do the LTL box labels from the shipping plan, send them to LHD, and they handle it all the way to Amazon.
It’s not about knowing how it gets there. Just have the Freight Forwarder take care of that part. It’s their job. 🙂
If you HAVE to ship by pallets, then that is a bit of a different scenario in which, yes, you have to use Amazon’s logistics to setup a drop off time and such, but 50 cartons is not so much that you need to ship via a container or anything. It is less than a truckload (LTL). Unless these are big cartons???
So, just use that option, in my opinion. That’s what I do every single time. I have NEVER used another option than LTL.