I very briefly tried a couple zwave light bulbs with a USB zwave adapter for Home Assistant, but couldn’t get it reliable. I do like the mesh + low power idea though and played around with ZigBee dev boards previously.

I have settled on mostly Tasmota firmware on ESP8266 based devices. Lots of switches (from the CloudFree shop among others), smart plugs, and other devices. I also like to assemble my own sensor/relay boards, which Tasmota is great for. I did have to set a fixed 2.4Ghz channel on one router, and later set “IoT mode” on my Unifi network, to avoid devices falling off the network. I also have flashed most of the devices, but am happy to do that (not so different from uploading an Arduino sketch once you’re used to it).

I have ESP8266 WiFi modules running Tasmota firmware for a few parts of this. Some report temperature (and humidity just for fun), I like DS18B20 sensors better than SHT30s which seem to have a bit more self heating. Then I also have Mitsubishi mini split heat pumps for which there’s a Tasmota control library. MQTT for communication + HomeAssistant for UI + AppDaemon for automation scripts in Python.

Examples of the UI in HA:

Yeah, every time I find some weird annoying behavior or some missing feature in MySQL, PostgreSQL is doing it right.

That said, also ask yourself if you really need a relational database, or whether an object store or append-only / timeseries db would fit better.