Smart switch without Wi-Fi and without an additional hub?

Hello everyone

In the multi-family house, the electricity consumption of the heating system needs to be determined. Unfortunately, there is no smart home installed to set up a suitable smart plug.

Initial situation:
- No Wi-Fi in the heating room
- No existing HomeKit or similar
- iPad is available in the household
- History of consumed electricity should be visible over one year

Can you recommend a product that makes this possible? It should continue recording during power outages (the heating is disconnected from power during the summer months).
I imagine a smart plug with internal storage that can be read out via Bluetooth or similar.

Thank you!

Ok, no Wi-Fi naturally limits a lot. But why not use a classic electricity meter/power consumption meter for the socket for about 10? It has no history record but can accumulate. If disconnected from power, read it shortly before in the summer, then switch it on again. From my point of view, the cheapest solution. Alternatively: repeater to the basement and for example a socket from MyStrom or Tuya (has its own app, no smart home needed).

What kind of heater is it? What load must the plug withstand? The heater is plugged into an outlet and is not hardwired?

Electricity meter plug-in adapter for a slim 10 at Amazon? The reading is then done by looking.

Thank you for your feedback.
- Yes, the heating is connected to a power outlet. Oil heating including heat pumps.
- A classic electricity meter is already installed, but it reset when the heating was turned off. Chimney sweeper, heating service, no heating period, which caused it to become inaccurate.

If no device with internal memory and battery is known, it will probably stay that way... Repeaters and constant Wi-Fi are too complicated for me.

Thank you!