Recently bought a used (but in great shape) Nexus 5X phone to give my son, who is in high school this year and apparently cannot live without one.
I knew that I wanted a phone I could flash with something like Lineage OS to de-googlefy it, but when I tried flashing it with the official version of Lineage OS it kept freezing at boot, or boot-looping.
After much dinkering, I finally stumbled on Maru OS. I was not very interested in the PC application. However, the phone OS installed and worked on the first go, did not have any Google apps, and had a clean looking interface. I am impressed so far. I almost want to try the PC usage, but it says I would have to get a Google Chomecast (and subsequently need to install gApps for that..maru - Your phone is your PC
Maru is a context-aware, lightweight, and open operating system that unites mobile and desktop computing.