In theory they work in stereo pairs. As someone who has been using them now for 18 months getting them to stay consistently paired is a nightmare for me personally; this is after changing every Wi-Fi setting under the moon and in the same room as the router.
My experience with the HomePod mini is that they don’t sound particularly good, if you can’t eq with Spotify they sound flat out bad, the stereo pairing is extremely problematic, and generally I regret not buying a Sonos or other product (HBO speaker even) , even at a much higher cost. They’re probably going to be sold as a pair for the £25 I’ll be able to get for them.
I appreciate a lot of people
Love them, perhaps individually as a small smart speaker they work, with the significant limitations of Siri smart speakers relatively speaking, but as a music device or paired to a MacBook Pro- I wouldn’t recommend them.
£160 is a long way towards a significantly better audio experience and the smart features largely rely on sending webpages to your phone. They’re not very smart on top of not sounding good.