I have several sensors in mqtt, for example water, electricity. But they are not displayed in the energy tab. I think that for display it is enough to have units of measurement. Let Home Assistant highlight that they are unreliable and may give incorrect readings. As an option, let them be displayed with a yellow warning . And please give verification if possible - for example, fill 10 liters of water to verify the sensor.
HA do not care about a sensor being unreliable.
HA just require that the right unit of measurement is there.
It seems m³ is right for water
To be displayed in the energy dashboard sensors must have the correct state_class, device_class and unit_of_measurement.
If your sensors are not supplying these required attributes you should open an issue. Not a feature request.
This is not true. e.g. energy sensors can be resetting types (e.g. daily energy) or always increasing forever. A correct state class is required to identify this so the energy dashboard can deal with the sensor correctly.
Closed as not an FR.