Power iot devices

Projects General Guidance
1

Let s say I have a new appartment and I can plan all required wires for my smart home devices.

What do you think is better:

  1. Put 220v, 0v, Ethernet wires to all controllable devices (switches, sockets, etc)
    Then a need a voltage regulator 220v to 3.3v for every device.

  2. Put 220v, 0v, 3.3v dc (voltage regulator is placed in the center of wires), ethernet.
    This way I dont need voltage regulators everywhere.

Are there any other variants and what problems can I face with my solutions?

2

12V on beefy cables: can run just about anything including LED light bulbs, and can directly connect to a battery and solar power.

3

power over Ethernet. if all you need are sensors and wireless, then your power needs are slight.
if you need relays, there is power at the relay that can be used.