First titbits of info regarding Google's second-gen Pixel phones has surfaced online via Android Open Source Project gerrit wherein one of the two next-gen flagships codenamed as 'walleye' was spotted running Android. The second next-gen Pixel phone codenamed as 'Muskie' will be the larger variant, which has not yet been spotted online.
Folks at Android Police have confirmed that there is no word on the specifications of the two leaked Pixel devices, although it is almost certain that the walleye will be the smaller variant while the Muskie will be its larger sibling.
Furthermore, the report claims that the details of both the Pixel models were obtained from the same source and in the same context. As far as the codenames are concerned, the walleye and muskie are named after the freshwater fish in North America wherein the latter is said to be the larger animal.
Apart from the hint of probable size, there are no other details available about these devices at the moment.