While other vendors continually push out new handheld pc models, sticking similar internals into different shell designs and gradually bumping up RAM or the Processor, the Steam Deck just keeps selling like hot tasty cakes.
Windows on a handheld is just bad. It's that simple. A Steam Deck competitor needs a handheld friendly controller focused interface that is at least as good as Valve's. Our just straight up ship with Steam OS and use Valve's.
SteamOS still has many instances of awkward UX and some frankly broken behavior, especially while trying to use community features, it's just that every other offering has been worse.
It's heavily rumored that Microsoft is working on their own handheld, and it will be interesting to see how that shakes up the market. If microsoft just makes windows controller/handheld friendly, it will greatly improve all the windows handhelds.
However I strongly suspect that we'll instead see the microsoft handheld be locked down, only able to run microsoft store games. It'll still probably do better than all the other non-deck handhelds that way, but won't really be a handheld "PC" if locked down that way.
Third possibility is that Microsoft might do both, release and locked down handheld and release some lesser improvements for navigating windows with a controller. This outcome would make sense if they have different teams working on both at the same time.
Considering Microsoft is dropping support for Windows Mixed Reality devices with Windows 11 24H2, effectively sending millions of otherwise perfectly fine VR headsets to landfill with no recourse. I can see them releasing a handheld with a "custom" version of Windows that allows users to install Steam, GOG, Epic, etc... then bait and switch with a future "feature update" that makes compatibility "too hard" to support or a "security risk". Maybe the desktop mode is a "developer only" option that gets disabled, or you have to enable third party apps like in windows 10 S and that ability gets taken away. I wouldn't put it past Microsoft.
Maybe I'm just peeved at Microsoft for deciding that my VR headset will be E-waste even though the hardware is fine, or ignoring the concept of user consent by enabling OneDrive cloud backups for local folders by default while basically forcing you to create a Microsoft account to install Windows if you don't know the right sequence of arcane f-ing rituals to create a local account. But I don't trust them...
Despite how good the steam deck is, any competition is good. With MS hardware track record I don't have the highest hopes, but again: any competition is good.
Don't get me going on the way the soft keyboard doesn't always work or that you can't use the thumb sticks when you have it up. I'm here to enjoy the Steam Deck gangbang but sometimes you get a random dick in a place you weren't expecting it.