Radiator setpoint controller

I am trying to configure the comet dect radiator control (AMV Fritzbox binding). Getting the actual temperature and setpoint works fine.
But I cant figure out how to make the set-temperature item to a control item?
Has the semantic class anything to do with that?

In the old days one uses the sitemap to define the controller but when using OH3 the model seams to serve this purpose



I added the standalone widget oh-stepper-card in the metadata to the setpoint item. In Admin->Settings->Model I can change the temperature and it looks like:

but in the home page it is still a readonly number and looks like: