There’s a Mac app called Lunar that uses DDC (a protocol for sending commands to a screen) to allow you to adjust the brightness and volume of an external monitor with the usual keys on your MacBook keyboard (in clamshell mode at least) or with a slider. Very convenient, can’t recommend enough.

Oh OK sorry but yeah I wouldn't use that. If this is usually supported on Dell monitors, I would bet it works on these.

Personally, I rarely adjust brightness on my desktop displays and my ZMK keyboard volume buttons work reliably cross-platform.

I you don’t need it, you don’t need it, but I don’t understand the first sentence. Many different displays support DDC, my Philips at home does and the Dells and I think BenQ that we have at the office do too.

My macbook is my work laptop and the bosses don't like us installing too many extra things.

I wish my personal was a mac as well, but I had to abandon macs when they abandoned me by not upgrading the mac pro for like a decade then kept me away by later ending support for eGPUs.