For a while, the story was that watches were going to take over the world. Now, the story is that the overstock has to be got rid of somehow.
https://techcrunch.com/2017/08/01/apple-watch-sales-up-over-...
I’d say they are simply trying to grow their market.
I think Apple needs this deal more than they admit.
I don't think Apple reports units shipped. Fitbit does. I don't know about Xiaomi. The numbers are a mix of reported units and estimated units.
These two statements are not in opposition if lots of watches are selling at a deep discount. When I google "apple watch amazon" the top link is a used model, second is a discounted series 1.