21.10 dual screen stopped working

I'm running Xubuntu 21.10, with stock kernel (5.13.0-20) on ASUS motherboard. Built-in Intel with DVI output, plus GeForce GT 430 card with HDMI.

I've had it set up for a long time with display :0.0 on the Intel DVI for my console, and display :0.1 on the GT430 HDMI, which is connected to my TV. All worked fine until recently, when after a reboot there was no HDMI output, and in fact no display :0.1 at all.

I have scoured the web, and found many different answers, including using the NVIDIA driver, but nothing has worked. Please help: my partner misses her TV!

xrandr shows just the console:

xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected 1920x1080+0+0 0mm x 0mm
   1920x1080     77.00* 

Relevant parts of /etc/X11/xorg.conf:

Section "Monitor"
    Identifier      "ViewSonic-console"
    VendorName      "ViewSonic"
    ModelName       "VX2439 Series"
EndSection

Section "Monitor"
    Identifier      "Panasonic-TV"
    VendorName      "Panasonic"
    ModelName       "TH-42A410Z"
EndSection

Section "Device"
    Identifier      "IntelGPU-DVI"
    Driver          "intel"
EndSection

Section "Device"
    Identifier      "Asus-GT430-HDMI"
    Driver          "nouveau"
EndSection

Section "Screen"
    Identifier      "Screen-Console"
    Device          "IntelGPU-DVI"
    Monitor         "ViewSonic-console"
EndSection

Section "Screen"
    Identifier      "Screen-TV"
    Device          "Asus-GT430-HDMI"
    Monitor         "Panasonic-TV"
EndSection

Section "ServerLayout"
    Identifier      "Layout-normal"
    Screen          0               "Screen-Console"
    Screen          1               "Screen-TV"
    InputDevice     "Keyboard0"     "CoreKeyboard"
    InputDevice     "Mouse0"        "CorePointer"
EndSection

Outputs requested:

$ xrandr --listproviders
Providers: number : 0

$ xrandr --query
Screen 0: minimum 0 x 0, current 1536 x 864, maximum 32768 x 32768
default connected primary 1536x864+0+0 406mm x 228mm
   1536x864       0.00*

Also, these lines from /var/log/Xorg.0.log may be relevant:

(II) NOUVEAU driver Date:   Sat Jan 23 12:24:42 2021 -0500
(II) NOUVEAU driver for NVIDIA chipset families :
...
    GeForce GTX 4xx/5xx (GFxxx)
...
(EE) [drm] Failed to open DRM device for pci:0000:01:00.0: -19
(EE) [drm] Failed to open DRM device for pci:0000:01:00.0: -19
(EE) No devices detected.