From https://github.com/JackHack96/dell-xps-9570-ubuntu-respin/is... from https://github.com/stockmind/dell-xps-9560-ubuntu-respin
What works out-of-the-box: Sleep/wake on Intel
What does't work properly: Sleep/wake on nVidia
I recall the issue is something to do with the chip that switches between the two video outputs?