That seems like its pretty close to us being abke to run linux on a newer phone

You can run Linux on current gen flagship arm SoCs. The framebuffer, gpu and cpu stuff mostly just works (with some support from hardware vendors). It's the rest of the device that's the problem: the phone part, the camera, sound, power management, etc.

I'd consider it a significant advancement. Phones have much tighter regulations than many consumer devices and this may not necessarily align with Valve's long-term business objectives, however, so I have some skepticism but would be pleasantly surprised if they pursued such an endeavor.

I'd say a lot of the backend stuff has the stars aligning now for such potential. Front end user experience is increasingly the sore spot now.

Not just this but if the compatibility layer on the snapdragon works on over ARM chips for other Linux distros, we could have desktop Linux on arm (including on new macbooks if you want).

Someone far more knowledgeable is free to correct me but that might have been the single biggest announcement they made

Doubtful, phone vendors already had access to binary blobs to run Linux (Android) on them.

It's no surprise Valve who is buying those SOCs is also provided with them.