Yesterday, three images of Logitech's new handheld were shared on Twitter by Evan Blass. Logitech quickly filed a DMCA complaint, inadvertently confirming the authenticity of the images.
The device looks to be about the size of a Nintendo Switch Lite, with an Xbox button layout and two grips on the back, like the Wii U GamePad.

One thing of note is the Google Play icon on the screen. Logitech did not mention anything about the device running Android apps, but it's still a welcome addition.
Outside of this, we don't know much else about the device other than that it will have a strong emphasis on cloud gaming.