While the added privacy measures are not as noticeable as notification snoozing, Picture-in-Picture, and other new customizations, there are a number of them in Android O. With this release, Google is specifically aiming to limit device identifiers and other information that apps can request.
At a system level, Android O will generate a random MAC address when devices are scanning for Wi-Fi networks to join. The initial packet sequence number for each scan is also randomized, while unnecessary information during the request is removed.
Unfortunately, MAC address randomization requires manufacturers to first update the firmware on Wi-Fi chipsets. At launch, the Google Pixel line and the Nexus 5X will be the first devices to support the feature.
For third-party apps, Google is trying to limit access to permanent identifiers that cannot be reset. Access to the device serial number in O is limited, while those for the camera and other Bluetooth identifiers will no longer be available.
The Android ID used by applications will now be different from app-to-app and user-to-user, though they will persist on install/reinstall. Meanwhile, third-party developers who do need device-scoped identifiers are directed to use the user resettable Advertising ID.
Lastly, apps cannot access the list of accounts and other services signed into on a device unless it is granted explicit permission by users or been pre-approved.