I might be wrong, but I think you need IOMMU if you want to pass the iGPU to a VM. Turn out that i3 6100i does support VT-d. Can't you activate it in the BIOS?
If you are using a container, you can pass devices via lxc.mount entries. Maybe
this post on this forum can help? At least, it will give you something to search for.
You might want to start with a privileged container first because unprivileged is more complex because of user and group mapping.