At launch, Steam Deck players made up 10% of the playerbase for The Pale Beyond. 9 months later after sales/etc that number has dropped to 5%.
Both numbers are significantly more than the steamOS user percentage (0.5%), so we can make the assumption that Steam Deck users make up a disproportionately high amount of games sales, and particularly full price sales for new releases.
People buying more games for their steam deck it’s coming out well for valve, given good reason to push steam deck for dev can benefit from it.