Not to be a wet blanket, but I predict failure (based upon the info in the article).
IMHO the main problem going to be processing power. A decent gaming PC has a CPU & GPU far more powerful than the Switch and if Valve tried to squeeze that into a portable system the battery life would be very short. But downgrading the CPU & GPU to a level where battery life if reasonable would make the system underpowered for anything more than casual 2D games.
Consoles like the Switch can get away with a lower powered CPU & GPU because developers learn how to do more with less or rework their game to fit within the system limitations.
Basing the SteamPal on Linux because
- While Steam supports Linux (and MacOS) this isn't true of the majority of games available through Steam.
- Graphics performance on Linux still lags Windows.
- Fewer PC games support controllers effectively vs keyboard & mouse
- Price - although not stated, I don't think this is going to be a cheap device