I don’t think they have produced enough Decks to change the statistics much. Deck is more of a prestige win: a major mainstream corp investing in Linux for consumers. Not to mention all work that Valve has put into dxvk and other libraries.

I think since the stats are based on web statistics, the steam deck probably won’t be counted unless the user switches to desktop mode and browses the web.

Though it’s possible the steam client accessing the steam store might count.