CyaogenMod was the first broad device, alt OS for Android. Pretty sure they support (at various OS levels) well over a hundred devices. A few years ago, they got some seed money and started their own for-profit company. It was a massive failure, just like any company that tries to monetize FOSS code (with the exception of Red hat). The OS, which is rock solid, faster, better, and more efficient than the base Google code will live on in a new form called LineageOS. None of that matters to you though, as Nexus devices are supported through Google directly.