VIDEO_CARDS="intel nvidia" might be important?
What are the xrandr commands?!
Missing xrandr commands
What are the xrandr commands?
are there examples on the page I am missing?
These commands should be listed now under the heading, "Configuration prior to starting X."
Modesetting DDX and glamor conflict
As of x11-base/xorg-drivers-1.19, the modesetting DDX driver has become the default for Gentoo. This driver uses GLAMOR to accelerate 2D graphical over Mesa (the open source OpenGL implementation) [intel wiki].
According to nvidia-drivers-375.26 documentation:
32D. CAVEATS ... Some versions of the "modesetting" driver try to load a sub-module called "glamor", which conflicts with the NVIDIA GLX implementation. Please ensure that the 'libglamoregl.so' X module is not installed.
Is glamor going to cause issues for users offloading Nvidia graphics display on Optimus devices?