They are making it from scratch. There are lots of sources but this is the first one I found. I assume they package it as well.

https://www.tomshardware.com/pc-components/ddr5/chinese-memory-maker-cxmt-enters-the-mainstream-consumer-memory-with-corsair-vengeance-ddr5-kit-chinese-made-dram-emerges-as-an-antidote-for-crushing-shortages

Foxcom assembles sub models into complete products. Still higher than slave labor level skills, but not as high as chip fabrication I admit. You need a skill base to assemble phones at a high level.