Home Assistant[1] is the best approach I've found for this. It's pretty amazing but has a pretty steep learning curve (although they're getting better and better at this). The real power of HA is the rich integration ecosystem[2], the Community Store[3], and that it runs locally (more reliable and much faster for things like motion sensors, etc). It expresses everything from every integration as an entity in various…
How do you handle network security? I wouldn't trust an IoT device on the same network as any of my family's computers or phones for example.
A second option is finding devices that can be flashed with Tasmota or ESPHome. This could also mean putting together your own devices with an ESP8266, ESPHome is basically plug and play for simple things like temperature sensors. You assemble the device, configure which pins to use via YAML, and then flash it to the ESP.
You don't even need to download a local build toolchain, the ESPHome add-on to Home Assistant can flash devices plugged into your computer just from the web interface, and then do OTA firmware updates.