True these transformers are of different type, they are ferrite core and are used at higher frequencies than the AC mains.
The resistance measurement you carried out must be with a simple multimeter, if it shows 0.8 Ohms, you may check if the meter shows 0.00 for no resistance (with the two leads of multimeter joined together).
In fact the windings are very low resistance with fewer turns of relatively thick copper wire.
These are used in switch mode power supplies. Better you buy one mains transformer with output of about 15-18 volts AC (even 12V will do as the filtered output will be 1.4 x 12 = 16.8V) that will serve the purpose. If you are going to use it for some purpose, the current requirements will also have to be considered before procuring the transformer.