BTW, our first Dot was one purchased to take audio output, not into a speaker, but into home stereo, but it actually is not used for that as much as we thought it would be. We really do not listen to Alexa music that much. We have so much digital music that the best (meaning quality) way to listen to music is our own music via stereo with our digital files coming directly from our NAS (or even just from a HD) to stereo.
Both Alexa and GH devices are more for casual convenience listening. and I feel the GH has better sound than Echo for music, so I listen that way most often now since the app I use on iPad can cast the music to GH and even to Chromecast device. Since music playing on iPad is being streamed to it by our NAS source, it is as high a quality as piping audio signal directly to stereo. If I want to bump up the music stream quality, I just direct the iPad to cast to Chromecast instead of GH and music is now coming from stereo with its video metadata content on TV
And, anyone who claims Google Assistant app is a substitute for a Google Home really doesn't know what they are talking about! It's like comparing apples and oranges.