After you're certain that you've followed my recommendations (you are using the AAPL,ig-platform-id that I suggested and removed the spoofed device-id), if you're still having issues with black screen, then you may need to review Dortania's guide for
boot flags. I don't need these boot flags with my RX580 (different PC), so I'm not familiar with them. For example, you might try without agdpmod=pikera and
definitely without igfxonln=1 and igfxagdc=0. You may need to try with agdpmod=vit9696.
A few notes about the boot flags:
- I've only used igfxonln=1 and igfxagdc=0 with iGPU. I can see how these might cause problems with your dGpu, so remove them.
- I don't know enough about the difference between agdpmod=pikera and agdpmod=vit9696. You should test without using either of them and then with each individually (not together).