To be clear, this is just an alternative Linux OS. The hardware shown in the thumbnail and article is just a mockup meant to represent a potential handheld. Part of their goal is to offer equally good support for all PC game stores (epic etc) vs the “steam first” experience of the deck.
Dedicated builds for the Steam Deck and other handheld PCs are to come later this year.
Choice of Linux distro has always been very fragmented though, and in my very limited knowledge it doesn’t really seem to be that much of a problem. They all basically do the same thing using the same core technology, so if both this and the Steam Deck are making use of Linux to be the OS and Proton to actually play the games then the rest is just a nice bit of user choice, right?