Brightness control "Up"/"Down" with xrandr (Ubuntu 22.04)

I am happily using the "brightness" command to control my TV as my primary display right now. But since I am working in a somewhat dim environment I was wondering if there is a way to not just set two precise values to keyboard shortcuts, but instead a more general commands for brightness "Up" and "Down"?

In the manual of xrandr I couldn't find the desired command. Perhaps I am looking for it the wrong way.

Edit: Here is some new info after the inxi command:

Graphics: Device-1: NVIDIA GF108GLM [NVS 5200M] driver: nouveau v: kernel
Display: x11 server: X.Org v: 1.21.1.3 driver: X: loaded: modesetting
unloaded: fbdev,vesa gpu: nouveau resolution: 1920x1080~60Hz
OpenGL: renderer: NVC1 v: 4.3 Mesa 22.0.5

This is what my terminal shows, just with less colours.
Perhaps I should add that the current solution is:
sudo xrandr --output HDMI-1 --brightness 0.7
and
sudo xrandr --output HDMI-1 --brightness 1
binded to global keyboard shortcuts.

(it's so nice to be able to organize the text just a little bit :D)

Edit.2

I am not sure why, as it happened many moons ago, but I am on the open source driver because I think I had some issues with the proprietary driver. Perhaps I will stay on my working setup now as I am already used to it. Thank you for your time even if we didn't come to a solution to this not-really-a-problem thing.

The "brightness" function is handles by the graphics drivers, not xrandr. Depending on your hardware, the brightness may be switched via the /sys/devices/platform/.. virtual file system.

To find the correct "switches" use the "find" command:

find /sys/devices/platform/ -type f | grep 'brightness'

To set a value somewhere in that tree you use:

echo OPTION | sudo tee /sys/devices/platform/some/component/mysystembrightness

where OPTION and the "some/component" path is hardware specific.

Edit

Your inxi reveals a NVIDIA graphics card with nouveau driver. Try to install the proprietary NVIDIA driver, which supports brightness control better.

After you installed the NVIDIA drivers do:

sudo gedit /usr/share/X11/xorg.conf.d/21-nvidia.conf

Paste the following into the file:

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    Option         "RegistryDwords" "EnableBrightnessControl=1"   
EndSection

Additionally add to your grub commandline: acpi_backlight=vendor

update_grub and reboot.