Owners of the Nexus 7 are able to enjoy Android 7.1 Nougat on their device thanks to a custom ROM from the CyanogenMod team, CM14.1. The custom ROM is based on Nougat and this brings the latest OS to the Nexus handset.
You need to install the USB drivers for the Nexus 7 onto your computer and then ensure that debugging is enabled on the device. Of course the handset should be rooted and you should have TWRP installed and plenty of battery life.
Connect the Nexus 7 to the computer and then copy the CM files to the SD card. You should then disconnect the tablet and turn it off. Go into bootloader mode and then hold down the volume up, volume down and the power buttons at the same time and go into recovery. You can use the volume keys to highlight and use power to select.
Go to wipe data/factory reset and confirm it and then wipe cache partition and then wipe dalvik cache.
You should choose install and then zip from SDcard and find the CM14.1 that you downloaded and confirm the installation.
You can then install the GApps package once the ROM completes installation and then head back to the main recovery and choose reboot.
You should now have Android 7.1 Nougat installed on the Nexus 7.