ASUS TUF GAMING Notebook FX795D "Failed to load module "nvidia" (module does not exist, 0)"

The laptop has dual graphics: AMD Radeon RX Vega 10 and Nvidia GTX 1650.

I’m trying to get X working with my Debian 10.5 install. I’ve been able to get it “almost” there, but the X server starts and then exits with the error mentioned in the subject.

I can confirm that the nvidia kernel driver is present (lsmod|grep nvidia), modules are present in /lib/modules/4.19.0*/updates/dkms (nvidia-current.ko, nvidia-current-modeset.ko, nvidia-current-drm.ko, nvidia-current-uvm.ko).

I also installed Bumblebee to handle the dual cards. It has a module, bbswitch.ko, but it does not load.

The system has UEFI firmware and the above modules have been signed (confirmed by hexdump and checking the end of the file for the string “Module signature appended”).

I an run “inxi -G” with the following results:

Device-1: Nvidia driver nvidia v. 418.152.00
Device-2: AMD Picasso driver: N/A
Display: tty server: 1.20.4 driver: modesetting tty: 100x37
Message: Advanced graphics data unavailable in console for root

And I have attached several files with various info:lspci.txt (166 Bytes) mokutil.txt (19 Bytes) nvidia-bug-report.log.gz (1.1 MB) nvidia-smi.txt (1.3 KB) Xorg.0.log (4.5 KB)
lightdm.log (2.8 KB) x-0.log (1.2 KB)
Xorg.0-2.log (4.5 KB)

lspci.txt output of lspci|egrep ‘vgs|[23]D’
mokutil.txt mokutil --sb-state output
nvidia-smi.txt output from nvidia-smi
Xorg.0.log log from running “startx – -logverbose 6”

lightdm.log 3 log files generated running lightdm -d --log-dir=DIRECTORY
Xorg.0-2.log (renamed to reduce confusion ;)

nvidia-bug-report.log.gz Per request. This ran without any difficulty.

Additionally, the following error was seen when installing nvidia-smi:
[ 271.744311] bbswitch: No suitable _DSM call found.

A web search shows that this _DSM message with bbswitch has been around for a long time, with no fix in sight, so far as I could find. Whether this has anything to do with the Nvidia driver is not known to me.

Additional info discovered while testing my Debian install with Secure boot off. There was no change in the failure to start lightdm, but I did get a couple of errors printed on tty7:
[ 6.387489] PKCS#7 signature not signed with a trusted key
[ 6.413622] PKCS#7 signature not signed with a trusted key

Why would this error be generated when Secure Boot is disable, and not generated when it is enabled? And is it relevant to the problem at hand?