Nothing new here, just sharing my experience. TLDR; I wish I had gone straight for Lilu.kext with NoVPAJpeg.kext.
I first tried turning on internal/integrated graphics in BIOS based on seeing suggestion it would work with my 18,3 SMBIOS setting. After doing so, boot time was many times slower than usual, and for the first time, I saw the purple/pink lines on the display during boot that others have talked about but I hadn't yet experienced. And, quicklook still couldn't preview JPGs.
So I turned off the internal/integrated graphics in BIOS.
Then I tried Lilu.kext with NoVPAJpeg.kext --- I just copied both to EFI volume in /EFI/CLOVER/Other --- and quicklook started working. Oddly, the purple/pink lines still appear briefly during boot. I thought they'd stop appearing after turning internal graphics off, but they didn't. This is mildly disappointing. Mostly I'm very happy to have quicklook working.