In order for Siri to recognise a person on a HomePod, the following steps need to be followed
1. Turn on Voice Recognition
2. Turn on Personal Requests
Both of these are enabled in Siri Settings on your iPhone.
Steps
1. Open Home App on iPhone
2. Tap Home icon in upper left corner
3. Tap your user profile under People
4. Turn on: Recognize My Voice
5. Turn on Personal Requests
If Siri does not recognize your voice, come back to this section and turn the "Recognize my voice" setting back off and on again