At least on the HomePod side, intercom is at best a half-baked feature and at worst an infuriation machine. It uses a cumbersome voice trigger ("siri, tell <room>…") to begin recording audio, with no clear indication of when recording began and no way to know for sure that the audio was directed where you wanted it to go.

To respond is similarly cumbersome and soon you give up completely. I can only assume it was designed by someone whose parents were killed in an intercom-related disaster and has sworn revenge.

I bought a mini for my office with this purpose in mind, but it has been a total waste.