The team at CyanogenMod is yet to make an announcement for the Android Nougat based build of the CyanogenMod ROM, but the folks enthusiastic over at XDA have already begun development for Nexus 5 CM14 ROM based on the AOSP sources released by Google for Android 7.0 Nougat.
Nexus 5 CM14 ROM development has been started by xda dev experience7, who claims the ROM will be available in a few days/weeks.
Installing CM14 on Nexus 5 will be similar to that of installing CM13 or any other custom ROM on the device. Also, since AOSP based ROMs like CM14 don’t come with Gapps in-built, you are required to flash Gapps package separately to get Google services like Play Store, Google Play Services framework, etc.
Thankfully, folks over at Open Gapps project have already released Android 7.0 Nougat Gapps of all sizes. You can get them at the download link below:
You can track development of Nexus 5 CM14 ROM on this XDA thread. We’ll be sure to update this post with download link once the ROM is available publicly.