I think this was being looked at all wrong. Pretty sure this is supposed to be a direct injection into their network hashrate. I followed a few useless links to the same story until I found
Bitmains Blog where they disclose their hashrate. I had no idea this existed, but assume with their regulations it must be fairly accurate.
So to me this 600 000 chips means they are trying to add ~183PH to their arsenal, currently ~367PH. I think that's around 3660 S17pro @ 50TH. With 144 chips/miner they could manufacture 4166 complete s17's if the order size is to be believed. Some could be set aside for defects and offspec units, not sure what the failure rate is.
It was also pointed out above that the order is split. Some of the chips are 16nm, meaning S9 variation perfect for their excellent power rates.
Notice how each of these articles is tied to the valuation they are hoping for. Pretty sure this is them bolstering 2 positions. First they want to look strong and heavily invested in themselves the network and the future. They are looking at an IPO after all, and they have an image to repair. Next I think they are trying to grab as many coins as possible for themselves again before the halving. They can get ahead of the Diff jumps if they take an entire order of chips just for themselves. Not hard considering they've sold out for months to come.