The description sparsely mentions that the bulb can connect through Bluetooth. But how do you that? The app has no option for that.
I think this is only supported for the initial setup at the moment. I don’t see any way to do it after that. My network was down the other night and I was unable to do local Bluetooth control with the app.
Yup, I even turned my WiFi off and like I said the bulb flashed green then flashed blue when I tried to pair in Bluetooth then returned to flashing green again. So I guess Bluetooth is really not supported in our cases.
Yes here is the FAQ section of Bulb Color Details still currently saying that this is a feature (unlike RGB rules/notifications which is called out as Coming Spring 2021). I think they just dropped the ball.
Has there been any further information on what to do during an internet outage?
Maybe one of these 
I have been unable to control the color bulb with just bluetooth also. I was just speaking with chat support and they said that you could. Bluetooth is used in initial setup but after that I can’t see how to connect via bluetooth. It isn’t listed as a previously connected device (Android v12).
Moreover, without internet, routines like bed time or sunmatch do not work. I found that out the hard way and chat support confirmed. So you can’t rely on this device without internet. They should really make that clear in the product description. If they have then I certainly missed it.
As it stands, in my use case I will need to purchase a separate timer that does not rely on internet, and of course, just use the bulb like a regular bulb unfortunately.