After a massive delay, Google has just introduced the Pixel 4a along with giving us a glimpse at the Pixel 5 and 4a 5G. But of course, companies have incredibly long development cycles when it comes to hardware, so it's no surprise that Google is already working on follow-up products. According to an internal Android document obtained by 9to5Google, the company already has software builds for the Pixel 5a, a foldable, and two more, not further specified devices.
The document supposedly lists all official software builds for all Google phones released since the Pixel 2 including the 4a, the 4a 5G, and the Pixel 5. That would mean the list encompasses all handsets still actively supported. On it, the publication also claims to see new devices: A Pixel 5a (apparently codenamed "barbette"), "raven," "oriole" and "passport." The latter is referred to as a foldable, while raven and oriole might be the Pixel 6 line, though 9to5Google can't confirm that. There's supposedly also a disclaimer saying that the new codenames might differ from the ones the new devices will get in AOSP, which have so far always been based on fish.
Back in May 2019, Google already confirmed to CNET that it was working on foldable prototypes, but the company said it sees no sense in bringing its own take on the form factor to the market. It looks like Google changed its mind, though it's also possible that it's just continuing to explore foldable options without immediate plans to release such a phone. The fact that some other axed prototypes are supposedly also found in the leaked document supports that the list is not a definitive confirmation for anything. All companies prototype tons of new devices, and only a fraction make it to the market.
Beyond that, the document is supposed to point to an October release of the Pixel 4a 5G and the Pixel 5, which would be in line with Google's regular fall schedule. It also says that the 5a is scheduled for Q2 2021, though with the messy 2020 Pixel lineup, it remains to be seen how Google will handle next year's phones.