You have not created a new USB map for your iMac19,1. See
@rafale77 's EFI attached
here. Use
@rafale77 's USBPortsimac.kext (you can't change SMBIOS mac models without creating a new USB port mapping).
In your config.plist, add PciRoot(0x0)/Pci(0x2,0x0) with property AAPL,ig-platform-id = 0x3E920003 (a "zero connector" framebuffer). You may need to experiment with the other "zero connector" framebuffer's listed
here. Make sure that when you enter the AAPL,ig-platform-id value in your config.plist, that you use "reverse byte" notation as I have explained
here.
Be sure to review ALL Known Issues
here and
here.
EDIT:
@lydahai - I reviewed the ACPI of a real iMac19,1 and see "AAPL,ig-platform-id" = <0300923e>" in the IORegistry. I think the PciRoot(0x0)/Pci(0x2,0x0) property that I provided should work for you.