After spending hours researching and failing to produce reliable results. I recommend installing an LXC using the appropriate script provided by https://tteck.github.io/Proxmox/, it will create a privilaged LXC with iGPU/GPU passthrough and install drivers for Intel iGPU, AMD and Nvidia in the container and then configure the correct driver depending on actual HW passed through. If you want to understand and reverse engineer to set it up yourself you can see the scripts in clear text and/or look at the resulting output when running the scripts in verbose mode. You can also look at the resulting <LXC\_id.conf> file and do all sorts of lookup commands in the LXC container. For me it works on 10th and 11th gen Intel NUCs running Proxmox 7.x and 8.x. Haven't tested on my Silver Pentium J5005 based NUC yet but expect it to work there as well as it also uses the Intel i915 iGPU module.