After successfully enabling and persisting the passthrough of the iGPU for the latest Intel NUC 10 (Frost Canyon), I thought it was worth experimenting with the Apple Mac Mini 2018 to see if the same could be accomplished with its iGPU, which is an Intel UHD 630. The biggest benefit in addition to unlocking the iGPU for general use is support for Apple's Metal API which gives developers access to the underlying GPU when building and testing MacOS and iOS applications. This is also quite timely as the Apple Mac Mini 2018 was just added to the VMware HCL!
My initial attempt failed when using the latest ESXi 6.7 Update 3 release. After enabling passthrough of the iGPU and rebooting the ESXi host for the change to take affect, the system would get stuck during boot up when loading the dma_iommu_mapper module. After speaking with Engineering, the issue is probably not related to dma_iommu_mapper module but some other module shortly after but without serial console output or ability to see terminal screen, it would be very difficult to debug the issue.
About to give up, my last attempt was try ESXi 7.0 and to my surprise the ESXi host fully booted up after enabling passthrough of the iGPU. It is still not clear on what might be causing the problem for 6.7 but at least 7.0 works!
Note: To be able to successfully power on a MacOS VM running on ESXi 7.0, ensure you have applied the recent ESXi 7.0b patch. You will need to go to the VMware Patch Portal siteto download and apply the update.
Step 1- Enable passthrough of the iGPU using the vSphere UI and then reboot for changes to take affect.
Step 2 - Navigate to Configure->Hardware->Graphics->Host Graphics and change the default graphics type to "Shared Direct"