To use an activity you say "Hey Google, turn on (activity name)" using the name of the activity you defined in the Sofabaton app. The activity will activate and the remote will switch to the selected activity controls. You can also create a custom 'routine' in the Home app and the activities will be listed as "scenes" in the device control list, so you could create a routine to activate an activity and maybe dim your smart bulbs with the same command. There is no way currently to control an individual device (Harmony hub does support this) so you can't, for example, pause playback or change the volume by voice control. A simple thing missing is that there does not seem to be a way to just turn off all devices. You can say "turn off (activity name)" but you need to remember the name of the last activity you used.