it looks like CopperheadOS is continuing:
Tweets from CopperheadOS, a security-centric Android-based distribution, are a good source of Android security news, since they’re stretching the boundaries of the open source android release.
CopperheadOS is “A security and privacy focused mobile operating system compatible with Android apps.“.
It appears the company is having problems trying to monetize an open sourced operating system. I hope they can solve things, they’re doing interesting security things with Android.