Send To Amazon - sending a pallet without units being put in boxes?

Hello, I am struggling to find an answer to this question.
I would like to send buckets of paint that are really well stackable on a pallet however, they are asking to put each unit in a separate box and print a label for it.
Has someone sent something similar without having to pack each unit in a box?
I have opted for Amazon’s Prep and labelling service, so I expect when they receive the units to go through the Prep Centre and be polybagged and put in a box for sale?

Thank you Amazon Community, Your help will be greatly appreciated!