I'm sure as long as there's a browser, a productivity suite and a media player it's going to be alright for most users. I also read they had a sort of Windows compatibility mode, similar, I think to the ones Apple has, to run Windows programs.
About SteamOS over Windows, I'm not sure Valve is running a charity either. Windows 10 and 11 have been, to some extent, free as you can download them from MS's site. I am running a free version that has an "Activate Windows" seal on the lower right side of the screen.
Of course just because it doesn't cost the user money, it might not mean it's free.
That's why I also asked about SteamOS over other distros. I'm not sure how much SteamOS fulfills Linux's "hacker ethos". It might be as much as Google's Android does. For a for-profit company it would not make sense to not harvest the user data of millions of users when you're giving away an OS for free...
Well, the Steam app has hundreds of millions of users and doesn't even read your web cookies or harvest any user data at all other than what you do while you are on their site, even though they could use that information to better sell you games.
It's true that Valve isn't running a charity, and that's why having an OS with the word "Steam" in it that automatically includes the Steam app would be a huge financial win.
As far as the "hacker ethos" goes, most of it wouldn't even apply to either Android or SteamOS. It's mostly just high-minded nonsense. But it starts with stating that sharing data is an ethical imperative and that all information should be free, which SteamOS fulfills by being open source. Now if you are worried about the other parts of the "ethos", Valve can't help it if you don't think that SteamOS is playful, artful or passionate.
Overall, comparing Valve to Microsoft or Google seems a little weird to me. Not all companies are the same and operate under the same values. Valve never laid anyone off even though they went 15 years without making any games, for instance. They've also occasionally let people freely use their IPs in commercial projects, which shows a generosity that very few companies have.