For those not familiar, Google’s Chromecast Audio was introduced in 2015, took the Cast abilities of the regular Chromecast and brought it to speakers, allowing you to bring new life to your potentially older in-home audio setup. You can Cast almost any music service to one, attach the Chromecast Audio speakers to audio groups in Google Home, and again, bring general smarts to speakers you may have purchased years and years ago for just $35 (or even cheaper when discounted).  Unfortunately, Google killed the Chromecast Audio at the beginning of 2019 and has yet to release any sort of replacement.

The Chromecast Audio was a great and very easy way to bring music to any room in the house at an affordable price, using existing equipment, without significant privacy concerns.  Killing it was a transparent attempt to get everyone to buy expensive (and intrusive) smart speakers and force people to scrap perfectly good older speakers, increasing needless electronic waste.  Bringing it back (perhaps with more output options for HD audio) would have an instant market.  Even at a 50% or 100% price hike, it's still very much worth it.