ddccontrol VS ddcci-driver-linux

Why do they not allow doing the same for external monitors using DDC? There are several apps that do just that.

Try ddccontrol on Linux or https://www.nirsoft.net/utils/control_my_monitor.html on Windows.

ddccontrol and gddcontrol works well

If I were you, I would take a look at ddccontrol. It's a utility that allows you to query the state and send commands to your monitor via the command line. I currently use it to increase / decrease the brightness of my monitor depending on the time of day.

i have always hated having to fiddle with the buttons on the back of my monitor to change things such as the brightness but now i have finally found a better way https://github.com/ddccontrol/ddccontrol

Before I look into automating it, I wanted to get it working first. For this, I have a tool called ddccontrol (https://github.com/ddccontrol/ddccontrol). But this needs root privileges. So I'm just wondering if there are other ways, since I couldn't find any.

There is an out-of-tree kernel module that exposes the DDC-CI interface as a regular brightness control, so any laptop-oriented brightness control tool will work afterwards.

Those tools use the kernel backlight system, which doesn't support external monitors out of the box. It's the same with Xorg. You can get the ddcci-backlight driver: https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/

To add to this: if you install ddcci-driver-linux GNOME should be able to control your brightness again. This removes the need for any extensions, and it's what I've been using for my monitor for the last few years.

There is an out of tree kernel module doing just that (integrating ddc/ci, the control channel for external monitor*, with the backlight system). And someone is working on upstreaming it

This is kinda a self promotion but for the brightness issue https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux may fix it. Or https://gitlab.com/YusufKhanAbdulHalim/ddcci-driver-linux/-/tree/master may fix it(if the first one doesnt work use the second one).

There is an unofficial Linux kernel module that allows userspace control of brightness (in a similar way to how laptop brightness is controllable):

https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux