I have a Ryzen 3900X (so no APU/iGPU) + 32GB + RTX3080, and just tried the 6.3VE USB installer.
A quick looks at the X server logs shows "cannot run in framebuffer mode". Upon Googling I see a thread in this very forum: https://forum.proxmox.com/threads/proxmox-6-2-installation-failed.70988/...