Any hints of it are gone now, but once upon a time not long ago, the Android Open Source Project gerrit was host to the speculative name of one supposed sequel to the Google Pixel.
From its reporting, Android Police believes the names are “walleye” and “muskie,” with the latter being the larger device. Both names refer to North American freshwater fish with the muskellunge typically being the larger one of the two.
The mention of “walleye” in the header image has since been removed from the changelog. “muskie” has also since been reportedly spotted in the gerrit.
Droid Life also has sources reporting that “taimen” is also being developed as an Android phone. Its namesake salmon makes its home in Siberia and Mongolia and typically weighs in at about the size of a muskie, though it’s rumored that the screen on “taimen” will be even bigger than that of the two others mentioned.
Google has a tendency to refer to its Nexus and Pixel devices internally by fish-based codenames.