That is good, the GTX 970 does not have another slot in the same IOMMU group.
Assuming that you want to passthrough the 970 to the VM, and use the motherboard Intel iGPU for linux, you first should set the Intel iGPU as the boot GPU with the video cable plugged into the motherboard.
Then you can bind the 970 to vfio. The guide you have been using is for Debian 9, so it is not ideal for newer Debian and Ubuntu based systems. Try the guide linked below, starting at binding the GPU to vfio. Replace amdgpu with nvidia or noveau(depending on which nvidia driver you are using), and the PCI IDs with the IDs of your 970.