So options 1 works fine and was already tested a few days ago. I can confirm option 3 now allows me to enable Spotify Connect by disabling Google Chromecast. For anyone wondering how to get the beta software, select the device in the WiiM app, then settings, then device info and join beta testing and select the Spotify Connect Quick Fix.
I can at some point turn chromecast back on using option 3 and revert to that use case so that Google Home connects properly (OK GOOGLE, STOP) or continue using spotify connect and be able to leave the building and still have music playing. Not worried about not having both.
My impression is that spotify connect is less likely to support "Jams", but will try again when the wife is back.
This has been a useful learning experience for me, and I really appreciate the WiiM team dropping in a beta fix to deal with the Spotify "glitch"
Google home has removed my device from the room and presumably will not ever stream to it (but that is for a later day to test)
I wonder for Google Home users if a "disable spotify connect" feature would be a useful option. Or have I just missed that?