I discovered an interesting tidbit regarding setting the HomePod’s volume:

1. The buttons on top of the HomePod change the volume in 5% increments on each tap.
2. The voice command “Hey Siri, louder / quieter”, “Hey Siri, increase / decrease the volume”, etc. changes the volume in 10% increments.

Also, Siri really shouldn’t need to hear the “Hey” in “Hey Siri” every single time I need something from her.

“Siri, just do it.”