@nivex LineageOS is an Android fork, a continuation of CyanogenMod. Lets you not have Google Play Services, but still means that whatever idea google comes up to make Android more shitty and more resource-heavy will affect you.
PostmarketOS is an attempt to make a new lightweight Linux-based system for phones. It's very WIP, supports like 20 phone models, out of which calling and SMS only work on Nokia N900. So long ways to go.
@lanodan @Wolf480pl @nivex And Purism Phone, which is completely independent, will be out shortly: https://puri.sm/shop/librem-5/
@lanodan @mareklach @nivex but SailfishOS frontend is proprietary.
There is also other stuff based on libhybris like Plasma Mobile but they have even less devices.