At the core of my home automation I use Home Assistant. I started with this on a Raspberry Pi and now have moved it to a virtual machine running on my homelab with MySQL running on another VM.
Connected to this I have various WiFi light switches, ESPHome on a few ESP8266s, a Sonoff Zigbee Bridge flashed with Tasmota, OctoPrint, and other Zigbee Lights and sensors. This allows me to monitor the temperature and humidity throughout the house and garden, automate lights, and keep track of my home whilst away.
It started out tiny and it is growing organically – which I think gives the best opportunity for me to learn without overloading from too many things to get my head around at once. I have to recommend if anyone wants to get started in home automation that growing slowly is the way to go.