In assuming you are not using your keyboard to set brightness because it’s an external display plugged into a laptop? Search for a DDC application for your desktop, it’s amazing, the brightness controls of your laptop will then control the external display as well. I use lunar on my MacBook, it was a revelation.
> In assuming you are not using your keyboard to set brightness
I prefer buttons on the monitor.
Using a game comtroller to change brightness is like driving a car from the back seat.
Or switch to HDR if you have a capable display.
I was pleasantly surprised that HDR also means you can control brightness - it is all software I that case!
And the brightness keys on an external Apple keyboard work.