I read through the OCLP guide and it is looking good. Good enough I might use it on my old 2010 iMac, which I have previously updated with an Nvidia Quadro K1100m card in place of the AMD/ATI 4650 that Apple provided when it was new. It already runs macOS High Sierra natively, the hack would be getting the unsupported Mac running Catalina or Big Sur. I am not interested in running Monterey, not really that fussed on Big Sur if I am honest.
I am sure the Nvidia aspects can be extracted from the OCLP setup files, once Monterey has been finalised/released. Until then there is no point doing so, as Apple could change the goalposts again, with the GM release.