If anyone is interested in this one…developers are still working on it. A while ago I gave them the following update:
Today I replaced the batteries of two of my smoke detectors that were displaying 1% battery level. Please see attached result. The one in the living room (yes, close to Homey) is displayed as having a full battery again, but the same thing did not happen to the one in the attic (in my office). Still it is connected to Homey as it does get notified when I test it.