Status update:
The "two cable method" with Macmini8,1 to enable iGPU acceleration in FCP was unstable for me. I would randomly boot into a black screen, get 'frozen' screen (but working mouse), get a couple of seconds of black screen in the middle of session etc. Things were even worse after sleep. Perhaps this was due to the lack of framebuffer patch?
Either way, I switched to the imac 18.3 SMBios .plist which would offer the alternative solution to the FCP problem. And this time it worked without any changes! So my guess is that maybe it would have worked the first time for me, if I had gone into BIOS and disabled/re-enabled iGPU when I tested the first time.
So currently I seem to almost have a fully functional system, except:
Media disabled after sleep - basically any app using media (spotify, quicktime, VLC player, FCP) will become unresponsive/not open. Apps like thunderbird, text edit (etc) open and close without any problems.
I have applied your "sleep and wake" terminal fix, as this was a necessity to even get back from sleep. I just tried it a second time but I still have the “media” problem. Any ideas on what to try next?