https://www.gamespot.com/articles/xbox-one-x-pre-order-guide-scorpio-and-standard-ed/1100-6452672/

August 25 update: If you've had trouble pre-ordering an Xbox One X, this might be why: Microsoft has announced it is the fastest pre-ordered Xbox console ever. The Scorpio Edition appears to be mostly sold out--although, again, you might have luck by continuing to check in at retailers that are currently out of stock. Microsoft says details on pre-orders of the standard edition will be shared at some point in September. We'll report back as we receive more information.

August 23 update: Retailers have sporadically been bringing pre-orders back online over the last day. As of this writing, Target has them back in stock again, although they may not last long. As with the SNES Classics, which have reappeared briefly, it may be worth periodically checking the retailer listings linked below to see if you can get lucky. Keep in mind, the Scorpio Edition will be available by pre-order only, though the system is functionally identical to the standard Xbox One X model.