Today I Learned that there is an app for macOS called DisplayBuddy. This app lets you control the brightness on your non-Apple external monitor using the brightness keyboard shortcuts.

It did not work for me at first, but the app was very helpful in letting me know that if I was using HDMI and an Apple Silicon Mac, I wouldn’t be able to control the brightness. I changed my monitor input to USB-C and it worked.

This app is available on Setapp, so it didn’t “cost” me anything.