"Warning: The Google Nexus 6P is no longer maintained. A build guide is available for developers that would like to make private builds, or even restart official support."

The devices link you included links to legacy builds/devices that are discontinued. The only Google phones currently supported on LineageOS are the Nexus 6 and Pixel 1/1XL. As another data point, the Samsung Galaxy S6 and S7 have no active support either while the S4 and S5 do.

This is where you should look: https://download.lineageos.org/

Apple's upcoming iOS version -- not just current, but the one that's not even released yet -- supports all iPhones released in the last 5 years. There's just no comparison.