I don't see this happening in the foreseeable future.

Making competitive phones is even harder than making a desktop, and they aren't investing in Linux desktop itself either, just the components they need. SteamOS works by not running a desktop in its default mode.

The threat profile feels scarily different too. SteamOS doesn’t feel like something I’d install a banking app on.

I don’t think they want to wander further into malware arms races. They don’t seem to really want to maintain their anti-cheat currently, it’s notoriously poor. I love Valve but I’m not sure I’d trust them with a platform I log into my bank with.