While I bet this will be solved soon enough, right now if you have multiple smart lights in a room you might experience frustration attempting to handle multiples in one sconce / lamp / etc. With how flipping dim these things are you probably need multiples.
TL;DR – create a custom “room” for a device with multiple smart bulbs, donate to the site.
In my particular scenario I’ve got a couple of smart lights (for kid sleep things, and because they love them,) in my kid’s rooms and suddenly it’s become a pain when the lamp and the two overhead lights all turn the same color and then Google wants to change all of them.
In my particular scenario: two overhead, one lamp, one 5yo ticked off.
Open Home app, open the room with all your lights, find the lights you want to group, move them, under rooms scroll all the way down to Custom Room and create it, do something like “Maggie’s ceiling” or “the Hydra Lamp”.
Now controlling the ceiling lights can be done with “hey google, make Maggie’s Ceiling lights green.” without picking up the things not in that “room”.
You can still global override and turn off all lights, but those in “Maggie’s ceiling” will no longer auto respond along with whatever’s hearing you in that Google Home room.
Side note – when you end up with multiple lights you start seeing which brand name’s backend servers are faster. So if it looks like you’ve got a stuck light might give it a second.
While I expect there will be a way soon to create groupings and assign to a light so you’ll be able to kill all lights in a physical room, this works for now.