New Detectors and Further Smart Compatibility

I feel that we should have a radon or gas leak detector added, also I feel there should be further integration with Nest systems. I like the Nest smoke detectors more than SS bc they have the smoke detector and the co detector in one which saves money, but also bc it doesn't set off from showers or boiling water and it provides a light at night for when me or my so stumbles through the house at night. And I like the fact that when the SS detectors go off they call 911 but I feel we should be able to use our Nest systems and make it so if I have the nest detector it will alert SS to call 911 if it goes off. And granted I would make the change to SS if it wasn't that Nest detectors interact with my Nest thermostat to offer a better energy efficiency. So I can't exactly just make the switch at least in my opinion.