Dead End? Google Assistant and Spotify

Is it really not possible to say “Ok Google, play music on [spotify connect device]”?

My partner and I both have Spotify accounts (2x media_players), and I’ve got a Denon AVR (denonavr integration, so another media_player). We both have voice match setup with GA and both have separate Spotify accounts setup in GA.

My understanding is it’s just not possible to use GA to say “Play music on [spotify connect device]”.

If that’s true, I’d like to be able to say “Okay Google, play music”, then “okay google, send music to big speakers”.

The first will start Spotify sending music somewhere random. The second I’m thinking I could have a template switch that gets turned on. When it’s turned on, it finds the speaker’s Spotify account and changes the source to the Big Speakers Spotify Connect device.

The problem is I would need to know who said the phrase - so whose music I should send. I could do some crazy heuristics to guess, but it’s never going to be as clean as knowing who just spoke.

Do I really need to do “Okay Google, Play Music” then “Okay Google, Activate Big Speakers for Idcmp” (or “for Mrs Idcmp”)?

I’d be up for adding a different voice assistant in the mix - but nothing else (Snips is dead, so really Mycroft) does voice recognition.

I could throw a Chromecast in the mix, but (as I understand it) idle Chromecasts don’t show up for Spotify integration, so it’s never going to be reliable?

Why’s this so hard?