How can I tell which driver is causing "Driver PNP Watchdog" BSOD?

Situation

I realized the other day that my mother's PC hasn't succeeded at a Windows 10 feature update for more than two years. It is currently running 1803, installed in June 2018. The update history log has multiple failure entries trying to update to 1903, 1909 and 20H2, most failing with code 0xc1900101.

When I try it manually through Windows Update, the new version is downloaded and supposedly "installed", but when it reboots, during the black screen with blue Windows logo and the circling dots, there is the BSOD with Driver PNP Watchdog error, then the installation rolls back to 1803. Sometimes it tries to install 1909, other times it tries to install 20H2. Same result in both situations.

I created a 20H2 install media, and if I try to run the setup.exe, overall same process, and the error code returned when the system rolls back is 0xc1900101 - 0x20017.

This system is 10 years old and has two 1TB SSD in RAID 1, and a 1TB HDD.

IMPORTANT: If only the 1TB HDD is connected, I am able to do an install from scratch using the 20H2 media, so I know it's possible to run the most recent Windows 10 on that machine.

My objective

Update this system to the latest Windows 10 version (20H2), without doing a clean install that would require me to re-install everything. I am prepared to spend time looking at the logs and using debugging tool to looks at dump files and stack traces to isolate the root cause of the BSOD (I am a software engineer).

Hardware details

• Dell Studio XPS 9100 ( Intel Core i7 930 @ 2.8GHz)
• Intel ICH10R Southbridge (Currently configured in BIOS as RAID, system unable to boot if I switch to AHCI)
• 8 GB memory, 1 TB disks are less than 40% full
• Currently running Windows 10 x64 Pro 1803
• Using only Windows Defender for antivirus

Things I have already checked

From How to Fix ‘Driver PNP Watchdog’ BSOD Error In Windows 10

• Check Volume Shadow Copy service

• sfc /scannow

• chkdsk C: /f /r /x

• DISM /Online /Cleanup-Image /RestoreHealth

• Tweak System Service Settings (rename SoftwareDistribution and catroot2)

• In device manager, there are no warning sign indicators (all categories are initially collapsed, and I also double-checked them)

• Ran Windows Update Troubleshooter

• Currently using only 1 SSD drive, raid configuration removed. Will try to see if I can change Sata mode to AHCI (trying to update in that configuration also failed) - Update: Can't reboot, "INACCESSIBLE BOOT DEVICE".

Additional info: Running SetupDiag (v1.6.0.0) on latest update failure only matches profile "FindRollbackFailure".

• Error: 0xC1900101-0x20017
• Last Setup Phase: Name "Finalize", started 20:27:09, ended 20:27:56, successfully completed.
• Last Operation: Name "Remove System Restore checkpoints", started 20:27:51, ended 20:27:56, successfully completed.

Update 2021-01-19

I gave up and reinstalled from scratch. Doing so, I learned a few things I'll note here in case others find this page with similar issues:

• The problem with the system no longer being bootable after switching SATA from RAID to AHCI in BIOS stems from the AHCI drivers not being enabled in Windows. The registry fix is described here by Microsoft for Windows Vista/7 and here for Windows 8/10.
• The ICH10R Intel RST driver that was "known good" for a while (13.6.0.1002) no longer seems to work in more recent versions of Windows 10.
• The Intel RST drivers versions 14.x to 16.x are causing an awful audio stutter when used with ICH10R. Using LatencyMon, we can see that storport.sys has extremely high latency. By applying the above registry fix and changing the SATA from RAID to AHCI in BIOS, storport.sys is no longer being used, and audio is stutter free!

Thank you Ramhound & TekkieBoy for taking the time to try to help me with the initial issue!