alt Hacker NewsOne comment mentioned Jolla. Another currently available option is [FuriLabs](http://furilabs.com). It runs atop Hallium/etc but you are effectively still able to daily drive a mobile Linux shell and contribute to the ecosystem if you want to see it grow.
Now with that said: so much work has gone in to Android (and by extension, Graphene) to improve on power usage/security/etc that I'm not sure I'd bother to actually run a mobile Linux device. The juice just doesn't feel worth the squeeze.
Furilabs was just in the news here because they discontinued their device models from a few years ago, and released a new device for a big price bump with _significantly worse_ hardware.
I know I would love to give them a try, but a 720 screen is an absolute non starter for me. It would be hard for anyone to sell me on just a FullHD (1080) screen in the era of QHD (2K) being industry standard. Additionally, I believe their FAQ even admits that their already low power devices only get a few hours of battery life.