args = [slicer_output_file, "--additional-module-paths", slice_installation_path, "--python-code", "print('Start Slicer from Blender!')", "--python-script", startup_slice_script_file]
process = subprocess.Popen([slicer_path] + args, shell=True)
When running this in Blender, can not install the Slicer addon properly. But it works in 5.6.