As per the long title, I changed my main Google password using one device (phone) while I was out of the house.
Back at home, in the Home App, I usually see my own home's name (Paul's House) and my mates home where I lived this time last year in the Homes list. In my Paul's House, I have several named rooms and different devices in each of them.
All I see now next to the right of the image of my Google account photo (so seems I'm logged in) is a prompt to create a new home, and all my devices are shown at the bottom, homeless and roomless, but still connected and working using toggles in the app.
If I talk to any of my speakers, every one of them tells me to "login using the Google Home app". I've been going nowhere quickly I'm afraid, and I can't voice control anything at the moment.