If you go for a dedicated GPU go for AMD the headaches that Optimus gives you with proxmox is just not worth it. IOMMUs are also usually all over the place in laptops.
Just maddening trying to get what should be something easy working on Intel. Totally done with that, going AMD, never looking back. And only Intel could market performance vs efficiency cores like some win to the user getting bilked. I'm looking forward to my Storaxa from kickstarter if they can figure out production.
Intel isn't wrong to try to to SR-IOV and virtual functions, so each VM gets what I would call a shard of the physical hardware GPU. However, I think the easier leap is to just go AMD and have much better Linux support. Just keep the iGPU on the Proxmox host, give the dGPU to the VM guest and be done. Wait for SR-IOV and the AMD equivalent to mature for some other year.