The success of the Steam Deck is encouraging at least one third-party vendor to bring out its own gaming handheld that will be running the Linux-based SteamOS instead of Microsoft Windows https://arstechnica.com/gaming/2024/01/why-more-pc-gaming-handhelds-should-ditch-windows-for-steamos/.

While compatibility with the overwhelming majority of Windows-only games still leaves something to be desired, the usability of the platform is already a definite selling point:

While Proton does come with at least some performance overhead, a variety of Steam Deck benchmarks show games running under SteamOS tend to perform comparably (or sometimes better) than those running under Windows on the handheld. That's also a huge change from the Steam Machines era, when Ars' testing showed that many SteamOS games ran significantly worse than their Windows counterparts on the same desktop hardware.

The Windows platform is just plain unsuited to a handheld gaming device:

Our review of the ROG Ally highlights just how annoying it can be to have to fiddle with Windows settings on a touchscreen running "an awkwardly scaled" version of the OS.

Though Microsoft has not been sitting still:

And while Microsoft has experimented with a handheld-friendly version of Windows meant for portable gaming devices, nothing public has yet come of the effort.

But unless it launches a much more concerted effort than it has managed to date, there’s a chance Windows may lose its undisputed dominance in the last major market where it has one: PC gaming.