AirPlay 2 is a small but important addition to Apple's audio world, allowing streaming on multiple devices simultaneously. Here's a list of the compatible speakers and receivers so far, and as available, the dates AirPlay 2 support is expected. Updated on November 4 with three new offerings from Naim.
The Citation 100 is a high-quality smartspeaker, and possibly an easy choice for people already bought into Harman Kardon, but otherwise there's not much reason to choose it over speakers from the likes of Apple, Google, or Sonos.
Smartspeakers are not just proliferating rapidly, but becoming de facto in the high-end audio market, led by products like the HomePod, Sonos speakers, and the Google Home Max. Harman Kardon's $300 Citation 100 is another emblematic example, equipped with Google Assistant.