Duo now has picture-in-picture mode for Android O users as the most recent update to the video calling application brings it up to version 11 and this was a feature that was tucked inside. Of course, since the picture-in-picture mode is something that is only available with the Android O developer preview right now, only those running the preview will be able to use the feature after updating the Duo app on their device, which isn't going to be too many people in the grand scheme of things when you consider all the users that actually have access to Duo. If you're running the Android O developer preview and you haven't gotten the latest update to Duo yet, you can can grab the APK from the button below.
If you've used an Android TV device on Nougat before then you should already know what the picture-in-picture mode looks like with the Android O developer preview, as it looks just like it does on Android TV. This particular feature looks to be the only new feature that was added in the app with this update, but it does look like the update included some groundwork that Google was preparing so that they could add other new features in updates that are coming further down the line.
For example, it looks like Duo will finally be getting a call history feature so that users will be able to go and see the history of everyone they've talked to through Duo whenever they need to check. What's more is that it seems Google is going to be integrating Duo's call log into the regular system call log, which means your Duo video calls will be consolidated with your regular voice calls to make things more organized and easy to get to, especially if the Phone and Duo apps are the only two apps you use for calls in the first place. Naturally, anything is subject to change so the picture-in-picture mode could be taken out in a future update, or it could just be disabled in a newer Android O developer preview and re-enabled once Android O is launched as a final build out to users. There is also no indication of when the call history feature will be added, though with Google I/O coming up next week it seems like a perfect time to make small announcements about apps that were introduced at last year's Google I/O.