Come on just do it already.
I know this may seem like an obvious move to you, but I'm curious to hear your thoughts on how this would best play out.
Are you simply imagining a handheld gaming device (similar to the Steam Deck or Nintendo Switch) and a 5G radio for connectivity, or something more interesting?
What would make that a better solution than attaching something like Razer's Kishi controller on to the 5G-equipped phone you likely already have?
I feel like one of Stadia's big advantages is that it will "run" on basically any device with a web browser. It doesn't need any specialized gaming hardware so I'm struggling to understand how a (likely expensive) dedicated device that can only run Stadia would offer a better end-user experience.