@tim Depends on what you want to do.
For shutters/lights I am using #shelly relays (concealed installation in the walls). I am running #esphome on them but with the stock firmware they can also be used fully locally over WLAN.
For windows/doors I am using cheap #zigbee sensors that you can stick to the frame. A good Zigbee USB stick is around 30 EUR. I have also added several #zigbee relays in strategic places to make the network more robust. Also all fully local using #zigbee2mqtt integration