The update is now available over-the-air and will reach these two devices over the coming days. If you don’t like waiting, you can always go to Settings > About Phone > Software update to manually check for the update. Also, here are the Android 5.1 OTA ZIP files links for the Z Ultra GPe and Nexus 7 (2012) 3G, if you want, you can sideload these ZIP files using ADB.
The update brings performance enhancements, stability improvements, bug-fixes and couple of small features.
HTC One M7 GPe is expected to be the next GPe device to get Android 5.1.

One reply on “Nexus 7 (2012) 3G & Sony Z Ultra GPe receive Android 5.1 update”
No update notification till now.. #waiting