Hello.
I would try to build it from ready made components, so avoiding designing a PCB. As I understand, the device should incorporate:
1. AC/DC power supply module - Wi-Fi takes a lot of current, simple solutions like a resistor or a capacitor to reduce voltage will not go.
2. Main controller - I would suggest ESP32 - it incorporates Wi-Fi, not expansive (about 12 usd), and, well, I have experience with it.
3. A small battery if some data needs to be saved in device by a blackout.
4. Resistor (Shunt) to measure the current (power) consumed.
5. A circuit breaker - as I understand, since the device replaces some circuit breaker it should retain it's functionality, for safety.
In this way, placing all components inside some 3D printed enclosure, the prototype can be made within several days.
As I understand, size of device may be an issue, so I would be very interested to know - what should it be? What exactly type of circuit breaker should it replace?
I'm an electronic engineer with 7 years of experience in 3D modelling using SolidWorks. Experience with Arduino and ESP32 controllers. Good technical background.
Best Regards
Anatolii