Interestingly, HTC has released the code for many variants of HTC 10 and One A9. While HTC 10 source code is available for T-Mobile, Verizon, Telstra and unlocked version, One A9 source code is available in many versions such as UK, EU, India, Arabic among others.
Check out: Best Android O features
For those not in the know, the source code helps third party developers in making better custom ROMs and custom kernels. The users, who prefer custom ROMs with added features, should start looking out for new releases in the XDA forums.
The Nougat source code for the HTC 10 and HTC One A9 is available for download now and weighs around 222MB for HTC 10 and 210MB for One A9.
Have a great day, developers!