Why not just buy a solid controller for your phone or tablet?

How could this hypothetical device possibly be better than an iPhone 12 Pro Max, Note, Galaxy S, etc?

Just to add to your comment, you can already turn any phone to a "streaming Switch" for $30, there are dozens of controllers like this:

https://smile.amazon.co.uk/dp/B08BRX3RT3/

the Steam Link android app lets you stream any of your games to your phone like this already. With a little more setup you can stream Wii games to your phone through Moonlight from CEMU and run them at 1440p60, while the Switch can barely do 720p30.

by having access to the steam pc game library, which is huge

Both major mobile OS platforms support steam link.

The games have to be run on some machine though

I could certainly see this being the flagship for the launch of a steam cloud streaming service a la Stadia, Luna, geforce now, etc. That does beg the question of how they would price it. I think they would have to price the hardware very aggressively or sell at a loss -- the cost of entry on these other streaming services is what, $50-60 for a controller? Although if gamers with big steam libraries could bring them with them to a streaming platform rather than re-buying then that would be a major differentiator.

On the local streaming front, I've struggled to do in-home streaming in a comfortable way with anything but a hardwired network between the PCs streaming. Maybe this will be different if they optimize it for wireless streaming, but on laptop wifi -> desktop ethernet I found it to be fairly high latency and lossy.

I think I agree with you pretty much on everything.

>But nobody is making a dedicated portable streaming device as far as I know, and it seems like something that'd fit really well with a streaming service.

NVIDIA kind of did it with the NVIDIA Shield some years ago, and I think they're still supporting it.

>NVIDIA kind of did it with the NVIDIA Shield some years ago, and I think they're still supporting it.

Shield no longer receives updates. GeForce NOW still runs on it, though. https://www.youtube.com/watch?v=pSWCJxS0-HA

Shield TV, the Android TV-powered settop box that most people nowadays call "Nvidia Shield", is still supported going back to the first version in 2015.

My recollection is that the original Shield was marketed as much for playing (Android) games locally as for streaming, and had a much more powerful GPU and CPU than contemporary mobile phones did. That's kind of losing the advantage of it being dedicated to streaming, which is that you could really cut down on the BOM.

Streaming is still in a awkward position, both user experience wise, the cost of the streaming games (with data caps), and the competitive aspect of some games.

People get blown away by the amount of data used by NVIDIA solution, Google Stadia is pretty much dead...

It's hard to say if streaming would be the win condition.