Did you manage to get your J4105 UHD 600 IGD to passthough ? I have a system with the same SOC and i am trying to do the same thing.
I can get the UHD showing in Windows but i keep getting Code 43 and a blank screen from HDMI cable (NO VGA ports).
Edit: I haven't tested HDMI output, however on my Seeed Odyseey x86 it would seem my UHD 600 is now working without Error code 43.
Will upload screenies and my files and settings soon enough.
Edit 2: So iGPU has passed through however HDMI port doesn't show a display just a blank screen. Will check bios settings for IGD and my see if I can swap to PCI-E
Edit 3: I have HDMI working now however in Linux Only yep go figure, Windows just shows a Blank screen so that must mean EDID issues as running Windows Natively on the screen it being tested on works fine.
Edit 4: I have Tested HDMI with Windows which doesn't work at all the GPU works fine but no signal out, However i have tried a Linux Live DVD (Ubuntu) and the good news is HDMI works fine without issues and HDMI Audio is also passing through without issues.
do you have this working in PVE 5.4.78 (6-3)?
Are you seabios or ovmf?
hostpci or args?
between the forums and the pci passthrough wiki i've tried almost everything and can't seem to get 43 to go away... really frustrating because on an earlier version of proxmox (6-2) on an apollo lake platform had this working fine with ovmf/q35...