20.04: Adjust display brightness in smaller steps with brightness buttons

I must disappoint you because I cannot provide a native way without additional software. Just indicating how I implement brightness keys with a smaller incremental change.

I use the utility light, which in recent versions of Ubuntu can be installed with the command sudo apt install light. Otherwise, it can be installed from the github page of the author.

The command light -A 1 will increase brightness by 1%, light -U 1 will decrease brighness. I bound these commands to the keys Ctrl+Brightness Up/Down. The utility allows to define a minimum brightness, so you never blackout your screen.