Smart home - cheap 1-Wire/RFM85W-433D 433 MHz sensors for 230V control?

I'm thinking about a smart home, but when I see the prices of ready-made solutions (150+ PLN/point) it makes me shy away.

I originally thought of 1-wire and in this thread:
https://www.elektroda.pl/rtvforum/topic2907636.html#14016086 we are already coming to a solution, but while looking for components I came across http://www.hoperf.com/upload/rf/RFM85W-433D%20RV1.0.pdf which at a price of 4.33 per piece intrigued me....

Idea -
sensor:
transmitter, optocoupler, resistors, diode - cost about £10 - the only problem is how to cheaply convert the 230V that is "at hand" to the 5.5V DC needed for the transmitter

Add to this a "hub" of, say, 100 receivers (because I don't know if you can have a receiver that receives from a hundred transmitters), connected to a computer and sending changes of state - a program to be written in one day. And we have a full analysis of what's lit up in our house, and you can even go further - you take apart the iron, put it in and never again worry "did I forget to turn off the iron?" I go on the internet and look to see if the "iron" transmitter is giving a high state or not

The next step would be the opposite - receiver, relay and we have control.

The only question is - do I need some kind of controller on the sensor side (probably yes) - if so, what kind (Inexpensive!) and what to give on the receiver side - (do I need a set of 100 receivers and some kind of controller to coordinate this, or one receiver and a smarter controller?

I would opt for the NFR24L01 - they have much more capability and the price is similar if not lower. The only drawback is the lack of software reset, which can be circumvented by adding a penny transistor to the circuit.

Processor - as I mentioned the STM32F0 family (they go for £10 each or wholesale for £6 or less).

Imho as a central station, you should use any processor (at least the same as in the rest of the devices) that can act as a bridge between the system and the computer, and leave most of the work to the program on the computer side (unless you are thinking about an autonomous system collecting data without the participation of the computer and, for example, immediately connected to a WiFi or ETH network, then you need something more powerful - STM32F3 or F4)

Personally, on NRF24L01 modules and AVR processors, I made a system with one central station connected to a PC and universal slave units, which could additionally act as signal "repeaters" in order to increase the maximum distances between the base and distant systems.

From what I can see the NFR24L01 is 2.4GHz - I'm afraid if in such a quantity (e.g. 50 pcs per site) they won't interfere with WiFi operation.
Personally, I prefer the computer to process the raw data because it's simpler, cheaper and, most importantly, faster.

Is this NFR24LO1 bidirectional or unidirectional?

2.4 GHz, but they won't transmit at the same time, it's a different channel anyway
They are bidirectional - read the catalogue notes

I did a bit of reading, didn't understand anything ;D
http://www.kamami.pl/index.php?productID=231723 The module costs £9, so the same as the RFM transmitter and receiver - so budget-wise - ok.

I understand that for this you need a processor that prepares the data packet (and processes the reception). I wonder if instead of an optocoupler you could give an ammeter - which instead of the 0/1 state will display the current - if the current is greater than 0 it means that current is flowing - and by the way additional data for the computer. Just are there cheap ammeters?

Yes, you need a processor.
You can buy these modules outside the shown shop even for half the price or cheaper - I once bought a dozen pieces for 3zl

I have recently seen NRF24L01+ modules on Aliexpress for just under $4 for 4 pieces + free shipping.
I myself ordered from ebay at $1.37 a piece.

I recommend you to look around with our slant-eyed colleagues, because for the price of one module with us you will buy 3 there.

WOW - indeed - to be fully satisfied I need a description of what to connect it to....