I use the Coral M.2 with KVM/QEMU, passing through the PCIe device. This works fine; the normal IOMMU group challenges apply here, I use the ACS override kernel patch to overcome my motherboard limitations.
The Coral USB I have had zero success passing through the USB device itself. I think the Coral driver cannot work with the increased latency. You might have success passing through the whole USB controller PCIe device but this is more complicated and has the same IOMMU group limitations. Anyway the PCIe device is more performant and is cleaner in my rackmount server setup so I sold the Coral USB.
I imagine ESXI has the same IOMMU group requirements as KVM/QEMU, so maybe this is something you’re running up against. I think you’re going to have to dig a lot deeper to figure out why it’s not working for you. My guess is that your motherboard does not have the right IOMMU groupings to passthrough the M.2 device or the USB controller.
You might be able to get this working with KVM/QEMU and the ACS override patch but it’s a long road. If you could add a PCIe USB card (I don’t think your Optiplex has any slots, does it?) you might be able to pass it though to ESXI if your groups work out.