Valve shouldn't give their blessing to SteamOS on the Ally. That should be Asus‘ job. However they could give Asus a cut on every game sold through their device on SteamOS (like a few percent). That would make it much more financially interesting for Asus and they might put an official team behind it, to support SteamOS.
Yes, thats how Open Source works or they can keep paying Windows. Asus knows their hardware much better than Valve does and has a much bigger interest in a good user experience, but currently lacks the incentive, because Windows is a „good“ paid alternative. Honestly I don't understand all the downvotes.
Open source just means you can get the source code, it doesn't mean you can take over a project.
Asus can't just take SteamOS, apply some driver tweaks, change some options, and release it as a SteamOS device.
A lot of SteamOS is proprietary, and Valve of course owns all the IP related to the branding. Asus literally needs Valve's blessing to do it.
Asus are certainly welcome to help Valve with their code, but Valve could also say no this is our project.
And of course they can fork the open part of SteamOS and brand it as something else, and not install steam/steamUI, but that's half the reason people use the steam deck. It wouldn't be SteamOS without that.
Okay, understood. May be SteamOS was the incorrect wording. I meant the Linux Kernel, Arch, Proton. I am assuming most changes are related to hardware and software compatibility which should all be open source.
It mentions that the work from Valve was for accessory support. So they may not be extending that much effort towards getting it on specific devices. Rather, I think they're working on generic PC support on the side.