Special audio was there before. That chip is from the Apple Watch and the prior gen HomePod was released four years ago and had an iPhone chip. Pretty weak update in that sense. Prior gen had six mics, new one has four. Prior gen has seven tweeters, new one has five. Prior gen had the ambient room temperature/humidity sensor (it was just set to inactive; they are going to make active the one in the mini). The new one is also lighter weight which typically results is a lesser sound quality. Matter support is a given.
All in all I would argue a weak four-year 2nd gen update. Not even so much as a single additional physical input or output, which some people had wanted of the product and was a commonly mentioned area for improvement in tech reviews for subsequent generations.