If using Android kernel eliminating rest of Android OS is the goal, Ubuntu Touch is being developed & run by ubports community[1] after canonical discontinued it.
I recently tried it on Nexus 4 & it is certainly capable for daily use. It is running on 16.04. It will provide regular Ubuntu OS updates but the kernel remains the same as the android version.
Since the android kernel is dependent on the manufacturer, once the updates are stopped, the device is at higher risk even if it runs Ubuntu Touch, LineageOS or other 3rd party ROMS though they release regular updates.
I believe, postmarketOS aims to address this in long term by using mainline kernel & at present uses android kernel for drivers without the user space? I'm not sure whether this offers any particular advantage over UBPorts Ubuntu Touch at its present state, but I really appreciate what they are doing & looking forward to use/contribute to it soon.
I recently tried it on Nexus 4 & it is certainly capable for daily use. It is running on 16.04. It will provide regular Ubuntu OS updates but the kernel remains the same as the android version.
Since the android kernel is dependent on the manufacturer, once the updates are stopped, the device is at higher risk even if it runs Ubuntu Touch, LineageOS or other 3rd party ROMS though they release regular updates.
I believe, postmarketOS aims to address this in long term by using mainline kernel & at present uses android kernel for drivers without the user space? I'm not sure whether this offers any particular advantage over UBPorts Ubuntu Touch at its present state, but I really appreciate what they are doing & looking forward to use/contribute to it soon.
[1]: https://ubports.com/