Strong start for the Xbox One X as was to be expected. Just like Pro, this shows there is an audience for mid gen consoles with higher spec. The launch week sales were equal to that of the Nintendo Switch and about half what the original Xbox One sold in its first week.
http://www.gamesindustry.biz/articles/2017-11-13-xbox-one-x-hits-80-000-uk-sales-in-first-week
EDIT:
Some additional info-
The first week sales of Xbox One X is over 80,000 in the UK, GamesIndustry.biz can reveal.
Retailers have shared data that reveal that Microsoft's new super-powered console has sold as many units in its first week as Nintendo Switch did in March (hardware figures are up-weighted 20%. Xbox One X raw data is at 67,000).
It's first week sales are also well ahead of PS4 Pro, which did a little over 50,000 back in November 2016. Indeed, it took PS4 Pro four weeks to reach the same number.
Of course, stock shortages of both PS4 Pro and Switch will have impacted the performance of those machines.
http://www.gamesindustry.biz/articles/2017-11-13-xbox-one-x-hits-80-000-uk-sales-in-first-week
EDIT:
Some additional info-
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