we have just managed to build the ICON model code on a local HPC but we also need the DWD ICON tools. According to the ICON Quick Guide, these tools are not openly available but our recently established contract with DWD would presumably allow us to obtain and use them.
Just to add a minor detail for others who stumble across this: DWD provides the icontools to national weather services for their production setups. For academic purposes, we recommend to use other tools, e.g. cdo.