I was able to get the right PciRoot tree with into my config.plistCoolbean,
To boot Big Sur you'll likely need SSDT-CPUR & SSDT-EC-USBX-DESKTOP.aml in ACPI, OC 0.6.9, Lilu, Whatevergreen, AppleALC, VirtualSMC, USBPorts.kext and SMBIOS iMacPro1,1. No need for boot-args other than alcid for your soundcard.
For the Aquantia you could try this. Your PCIRoot settings may differ so add it in Devices using the + button:
View attachment 3251
Btw that device-id is this: 4b00000001000000010000003f0000000100000002010c00d041080a0000000001010600041c0101060000007fff0400160000006200750069006c0074002d0069006e0000000500000001
And the last bit for model says Aqtion.
After i updated the PCI Root path all the changes show up in IORegisterExplorer to Aquantia,
---but did not work with device ID you gave and when I use it the Device Name would not show up in Hacktool so I just left it out now seeing if that works but still no luck
If you have another address to try for device ID, I can try it.