But, if you have installed a few Fibaro Relays (to automate your electric boiler for instance), and Hue Bulbs, you are already mixing Z-Wave, ZigBee, and I think you're maybe using Home Assistant, or trying some DIY using Raspberry Pis.
I think these questions are important. You'll be able to take fast and precise choices for your future system. For instance, if you need a plug and play, internet connected HVAC management and smoke sensor system, and you don't want to spend time to make it work, or to expand your system, maybe a Nest Thermostat, and its smoke detectors are enough. But, if you have installed a few Fibaro Relays (to automate your electric boiler for instance), and Hue Bulbs, you are already mixing Z-Wave, ZigBee, and I think you're maybe using Home Assistant, or trying some DIY using Raspberry Pis.