This is a small wrapper to more easily control your monitors' brightness.
It was hacked together in a few minutes or hours. This program works for me, but very unreliably (probably my Dell monitors' fault). I do not plan to work on this, but PRs are welcome anyway.
ddccontrol is used to send commands to the monitor(s), and you might want to use that or ddcutil directly.
You probably need to change the I²C addresses in main.py.
./main.py 1:100,2:50 sets monitor 1 to 100% brightness (assuming 100 is the maximum, which is not necessarily the case) and monitor 2 to 50% brightness.