Anything in my EFI glaringly problematic?
Well...
1. Your sources of ACPI documents do not match your OC 0.8.3 file dates, which should closely match you're "xxxx.efi" dates (i.e. 8/1/2022).
1a. Your "SSDT-EC-USBX-DESKTOP.aml" file dated 8/13/22 is 8 Kbytes, whereas the "SSDT-EC-USBX.aml" file supplied by OC 0.8.3 dated 8/1/22 is only 306 Bytes. If you look at your file in MaciASL, it is really huge, probably a nightly build. Don't think you want that and should use the proper one.
1b. Your "SSDT-AWAC.aml" file dated 8/13/22 is 359 bytes long, whereas the OC 0.8.3 Release "SSDT-AWAC-DISABLE.aml" file is only 78 bytes long. Again it looks like you are using a nightly build. I repeat that you should use ACPI documents that are supplied with your official build.
1c. Again, a nightly build for your "SSDT-PLUG-DRTNIA.aml" file is dated 8/13/22, vs. the "SSDT-PLUG.aml" OC 0.8.3 file dated 8/1/22. 979 vs. 900 bytes in length. Yours might work... dunno.
2. In EFI/OC Kexts, I don't think you need "NVMeFix.kext." At least I don't, and I use a Samsung 970 Pro 512 GB M.2 NVMe SSD in my Z370 computer.
3. In EFI/OC/config.plist/Booter/Quirks, I have found that my Z370 does not require "SetupVirtualMap" to be set to YES, although it works okay like that. But some folks say their setup only boots with it set to NO. Mine is currently at NO, and that works fine too. (You might want to try "NO" and see if it helps.)
4. In config.plist/DevicePoperties/Add, second item, for AAPL,ig-platform-id, did you ever try the OC guide's initial recommendation to use 07009B3E? Did you get a black screen with that?
5. In config.plist/UEFI/Quirks, you have "EnableVectorAccleration" set to NO. Are you sure that's right?
I hope you have better luck this time!