I too now have one Sonos machine just for notifications. I didnt like being a creditor to Qantas in this Covid19 environment, so cashed out out all my ff points, for 3 Sonos devices. One is currently my notifications device in my office.
I use it for open garage doors, open (other doors), and arrivals. Via Node Red. Works really well. I also have laundry notifications.
I've got cheap (fleabay, craigslist) dumb powered speakers scattered through the house, each attached to a RaspberryPI or laptop. The speakers are accessible as squeezeplayer devices, and Hubitat can send voice/sound alerts via RM & HSM and the Squeezebox driver. So far, so good. However, the previous audio doesn't seamlessly resume after an alert.
I use a Samsung R3 in the kitchen for first floor announcements and echo dots throughout the house. I gave up on Sonos for notifications specifically for the resume feature not working.
The echoes gen3 devices do resume so those rooms using music have no issues. My Sonos are now only for great whole home audio.
I would LOVE to see a screencast or written instructions of someone setting this up with Google Home. Are there any guides on how to setup floating around?
I just implemented Echo Speaks v3 and the first thing I did was tie a similar action to my Good night routine. It's triggered by my shutting the bedroom door, the lights dim to about 50%, and now Alexa plays soft piano music courtesy of SiriusXM for 1 hour before shutting off. It's a great way to fall asleep every night!