iMac late 2013, Sequoia 15.3, Nvidia GeForce GTX 780M, no external display

Hello everyone,

I've been using this old iMac flawlessly for a year and it's fantastic. I had the opportuniy to acquire a LG ergo Ultrafine 32UN880... for 140€ and it's great (I broke the USB C port though) and I'm using it with my MBA M3.

Now, I purchased a Mini DP to DP cable to use the monitor with the iMac. The iMac "sees" the monitor but gives me a black screen.

I've read that I need to add: agdpmod=vit9696 with OpenCore Configurator. Can someone please help me doing this?

This is what I have when I select:
7C436110-AB2A-4BBB-A880-FE41995C9F82

keepsyms=1 debug=0x100 -lilubetaall ipc_control_port_options=0 -nokcmismatchpanic

To be honest, I have no clue what this means...

1. should I just add this argument agdpmod=vit9696 to the line?

2. Has anyone tried?

Thanks a lot.