Screen Backlight Not Working on X1 Extreme on Tumbleweed

As it says in the title, I am trying to get screen brightness controls working (ideally via the built in keyboard buttons on the laptop). Thanks in advance for any help.

I am running Tumbleweed (updated today) on a new Thinkpad X1 Extreme (4K). I have turned on discrete graphics in bios (rather than “hybrid” graphics) so I should be using only the Intel graphics and not the NVIDIA card, although that is all that I see in lspci:

# lspci | grep -i vga
01:00.0 VGA compatible controller: NVIDIA Corporation GP107M [GeForce GTX 1050 Ti Mobile] (rev a1)

# modinfo nvidia
filename:       /lib/modules/4.19.11-1-default/updates/nvidia.ko
alias:          char-major-195-*
version:        410.78
supported:      external
license:        NVIDIA
suserelease:    openSUSE Tumbleweed
srcversion:     E6823ED882C76894D74F1C2
alias:          pci:v000010DEd00000E00sv*sd*bc04sc80i00*
alias:          pci:v000010DEd*sv*sd*bc03sc02i00*
alias:          pci:v000010DEd*sv*sd*bc03sc00i00*
depends:        ipmi_msghandler
name:           nvidia
vermagic:       4.19.11-1-default SMP preempt mod_unload modversions 

I don’t have anything in “/sys/class/backlight” nor do I have any plausible “backlight” or “brightness” files/directories in “/sys/”

“xbacklight -g” reports “No outputs have backlight property”

I have tried updating grub with ether