No progress by me. I've tried DSDT&Kexts from here, and also from
https://github.com/Xmingbai/HX99G-Hackintosh (this EFI work appears to use an actual HX99).
I am currently using the system (monterey 12.6.3) but with only the two adjacent read USB type A sockets active - one supports a normal collection of USB2 only devices, and the other can have one USB2 or one USB3 device (i.e. I can have 2 fast internal nvme disks and one fast external usb3.2 disk, and I have a USB2 network interface). I have to balance hacking time with work time.
For Linux, I've found that the pop_os! Linux correctly detects all hardware including the 6600 GPU and usb3.2 (looks like thunderbolt is also working but I didn't check that). For BSD, you'll need FreeBSD-14-current in order that the latest linux drivers for navi23 (6600) can be installed i.e. don't bother with FreeBSD-13.x. When working on adjusting monterey, I find that the pop_os! install USB disk offers a fast way to quickly access the EFI setup and restore a known working version if something breaks.