to properly find out how many Drivers were written specifically for my SUBSYS is to search in the Dell Model Pack for my laptop for my SUBSYS which is 08321028

Get-ChildItem 'D:\OSDDrivers\Expand\DellModel\DellModel X9 Precision 7730 10.0 A07' -Recurse -Include *.inf -File | `
Select-String '08321028' | Select Path

The results are not so spectacular. Out 178 INF files in this Dell Model Pack, only 7 matches (3%)

• Realtek SD Card Reader

• Intel Ethernet

• AMD Video

• Intel Video

• Nvidia Video

Conclusion

In this particular case, this example should demonstrate that the number of OEM Customizations is not significant. And finally, wasn't the OEM Customized Drivers by Realtek, Intel, and Nvidia, also found in Microsoft Update Catalog?​