Finally got it to work.
I added the working xorg.conf for nvidia prime as an attachment.
Maybe it will help someone else too.
Please tell me if you see anything in it that shouldn't be there.
Thanks to all who helped me with this.
--
Linux-gentoo-x86_64-Intel-R-_Core-TM-_i5-7400_CPU_@_3.00GHz
COMMON_FLAGS="-O3 -pipe -march=native -ftree-vectorize -ffast-math
-funswitch-loops -fuse-linker-plugin -flto -fdevirtualize-at-ltrans
-fno-plt -fno-semantic-interposition -fno-common -falign-functions=32
-fgraphite-identity -floop-nest-optimize"
USE="-* git verify-sig rsync-verify man alsa X grub ssl ipv6 lto
libressl olde-gentoo asm native-symlinks threads jit jumbo-build minimal
strip system-man"
INSTALL_MASK="/etc/systemd /lib/systemd /usr/lib/systemd
/usr/lib/modules-load.d /usr/lib/tmpfiles.d *tmpfiles* /var/lib/dbus
/lib/udev /usr/share/icons /usr/share/applications
/usr/share/gtk-3.0/emoji"# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig: version 525.147.05
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0"
Screen 0 "Screen1"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
EndSection
Section "Files"
EndSection
Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/input/mice"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection
Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection
Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Unknown"
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "modesetting"
VendorName "NVIDIA Corporation"
ChipId 0x0
ChipRev 0x0
IRQ 0
EndSection
Section "Device"
Identifier "Device1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BusID "PCI:1:0:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
Option "metamodes" "1920x1080 +0+0 {ForceCompositionPipeline=On}"
EndSection
Section "Screen"
Identifier "Screen1"
Device "Device1"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
Option "metamodes" "1920x1080 +0+0 {ForceCompositionPipeline=On}"
EndSection
