os – Which operating systems are available for smartphones with x86 or x86_64 architecture, such as the ASUS Zenfone?

Those smartphones built with Intel processors (such as: various versions of the ASUS Zenfone; Lenovo P90; Lenovo K80; ZTE Geek V975) were shipped with Android compiled for Intel architecture. Which alternative, in the best case open source operating systems are available, that can run on Intel smartphones?

The Android x86 distribution, for example, only runs on PCs, not on smartphones. As far as I can tell, LineageOS is the only system for which installation instructions for Intel smartphones are available.