Smoke Alarm & CO Detector

I need to replace the units in my house. I'm not sure if it's relevant, but I have a heat pump and AC. I want something that can connect to Google Home. I also want the units to "talk" to each other (if basement alarm detects, all alarms sound). Or is that not recommended since you can't determine origin? Lastly, I want a unit that detects lower readings. I read that the threshold is 70ppm but that lower readings (ie 65 ppm) are still dangerous. Any recommendations?