I managed to run a dimmer with rules.
Used the info from the following https://community.openhab.org/t/yet-another-wakeup-light-rule/41941
This works perfect.
Since I have different dimmers i would like to define a function (eg with phython) by providing in a signature item-name, min/max value dim-step.
As a result I could implement in the rules file with a 1-liner call complex operations.
A how-to-tutorial would be great. I (newbie) didn’t find something.