Samsung made the S7 and S7 edge Nougat beta official through the Galaxy Beta Program app the other day, expanding the countries that will dole out the sweet desert from its servers to U.S., U.K., and, shortly, China.
There are caveats, of course - in the UK, the beta will be available only on "a non-operator locked device or have purchased an open market version," and overall it will be distributed on a first-come-first-served basis, so no need to hurry up, the invites might have been taken already. Ditto for the US. Fret not, though, as you can sideload the thing with minimum trouble - no need for root, TWRP, etc. - following the steps below.
1. First and most important order of business - go to the "Lock screen and security" settings, and set up a PIN number! You will be asked for one on first reboot after the official Nougat firmware is installed. Go to Settings > Lock screen and security > Secure startup > Require PIN when device powers on;
2. Download and extract Samsung's firmware upgrade Odin software, v3.11.1;
4. Press and hold Home + Power + Volume Down buttons to enter download mode on your phone;
5. Start Odin on your computer, and connect the phone to it until you get the blue sign in Odin;
6. In Odin, add the respective firmware files in the slots on the right, and make sure the Re-partition box on the left isn't checked;
7. Click start, and wait for the firmware upgrade, then enter the PIN from step 1 upon reboot.
source: henklbr (XDA-Devs)