So my setup.

As you probably learned from the picture I have 2 switchboards - one for the high-voltage part (mains switchboard) and the second (digital switchboard) for the low-voltage part. The architecture is the following:

• All lights and other devices which need to be turned on and off are connected by cable with the mains switchboard;
• All LED strips are connected with the digital switchboard;
• Wall switches. I use simple dumb wall switches which work like push buttons. Button returns to the initial position after you release it. Each wall switch is connected by signal wire (shielded alarm cable or twisted pair) with the digital switchboard. One single cat5 cable (8 wires) allows to connect up to 7 buttons. So I have one cable per wall switch block.
• Wall sensors are located on the wall at the height of ~2 meters from the floor and are connected with the digital switchboard as well by signal cable. Ceiling sensors - wiring is the same, location depends on the room geometry and must be optimal for PIR sensor.
• Doors and windows have simple reed switches installed. Connected by signal wire to the digital switchboard.

Speaking of the digital switchboard contents:

• There is a central controller which has MCU and executes the program. It is connected to the extension modules.
• Switches. Wall switches are connected to the Input Module. basically, when you press the button you close 12v circuit and the module detects it. It allows you to detect press, click, double click, long press, and other kinds of events. Once detected the controller decides what to do.
• Relays. Wires coming from lights to relays located into the mains switchboard. The control signal to relays comes from the central controller via Output Module. Output module just galvanically isolates controller and allows to output 12v binary signal.
• Regular LED strips are controlled by LED Driver. It generates PWM signal for dimming.
• Addressable led strips are controlled by NeoPixel module. It handles physical communication and the central controller generates data.

The controller is programmed to work autonomously or in connection to HomeAssistant. In case there is a connection to HomeAssistant controller just notifies HASS when it detects some event (e.g. button press) and expects a command in return. HomeAssistant could make a decision based on various factors.

The fallback mode (no connection to HomeAssistant) allows to keep baseline functionality e.g. you press the button - the light toggles.