ZHA smooth dimming osram light group

Hello

I’m using iobroker and want to checkout home assistant.
In 2 rooms, I have one group with 6 Osram lightbulbs each (Hue compatible). One way to control them is a Hue dimmer switch.
What I figured out with iobroker is, that I can’t just de- or increas the brightness. The rate of commands to the bulbs is limited. Also, I have to put them in a zigbee group to get identical behavior of them.
My solution in iobroker is not to set the brightnedd. Instead, I use transition_time and brightness_move. When the dim button is pressed there is one command to dim and when the button is released, both endpoints are set to zero which stops dimming.
The scripts are more complicated than I thought in the beginning but they are working.

My problem now with homeassistant and zha is, that I’m not able to get it work. The devices are recognized. My hue dimmer is recgonized and I can connect automations for it. I hoped that I could just do a simple automation and connect the button with the in-/decrease entities. That’ not really working, dumming is not smooth and gets stuck.
So I wanted to do it like I did in iobroker.
My problem is, that I can’t select the required endpoints for the zigbee group. There is only in-/decrease brightness as action in the automation dialog.
The zigbee group is not really shown as device. It seems to be part of the zigbee coordinator. In the entities list I was not able to find anything related to the zigbe groups. Only in the automation dialog I can select some actions for them.
At the moment I’m alittle bit lost here.

Do I also have to use the transitions like in iobroker?
Can I use the automation wizard or do I have to deal with yaml?
How can I find the endities I need?
I assume they exist for single lights but not for the group.

Thank you very much.