Nvidia installed but not used

I am new to NixOS trying to learn
i tried to install Nvidia driver using this guide

seems installed but when i go to about system seems using the intel driver and not nvidia
my laptop has intel and nvidia quadro 1000M cards

also seems wayland used although X11 server is enabled.

Enable the X11 windowing system.

services.xserver.enable = true;

I a looking for easy way to install and frce the system to use nvidia driver.