Collected the new HomePod today, got it home & it needed a 1.69 GB download of the latest OS before I could set it up as part of a paired HomePod stereo set.
Thorough;y impressed with the distortion-free full volume capability, plus the paired set has a much higher volume level than just one HomePod.
Single HomePods do work in stereo but the separation is no greater than the width of the device.