Here are the main components of my system, which has become a bit of a collection over the years:
Home Assistant on RPi
zwave USB stick
a number of lights, switches and multi sensors on the zwave network
A cluster of four RPis for various scheduled and transient tasks (data ETL, solar energy forecast model training and forecast generation, house battery and EV charge planning and execution, scraping and processing council bin collection schedule)
two RPis handling motorised curtains and cooling fans in home cinema
three ESP2866s running ESPHome controlling relays for switching sauna, floor heating and water immersion heating on/off
ten ESP32s running WLED controlling LED strips inside and out