I don't know the Amazon down jacket but I do have this:
https://www.decathlon.com/collections/mens-down-jackets/products/mens-trek-100-hooded-jacket?I had doubts when I was told of this and the unknown brand, but I am impressed on how warm it gets for something so light and small when packed, and comes with a hood which I feel is a must if I only pack one insulating layer.
Truly the warmest down I have including a North Face that is suppose to have twice the loft and is a lot heavier.
It costs $45
