I think oxygenating plants would be far better than using power to heat or oxygenate the water.
Our front garden, as well as the pond, is filled with indigenous plants. Dogwood, holly, heathers, yew trees, hawthorn, an enormous broom bush, ancient fruits such as quince and medlar alongside apple and pear, undersown with bluebells etc. These plants grow naturally in this environment, in this climate and with this soil type, because that's what they have always done.
Not that it's entirely native, we have pyracantha and a pocket handkerchief tree and some lillies, together with flag irises in the pond...
Anyway, the point is that, by choosing local species, we haven't been out there to do any maintenance in 2 years, because we don't need to. Everything gets rotted by local fungus or eaten by local birds or local insects, which are themselves then eaten by the local birds.
Having something which needs heating through the winter just sounds so... I don't know... contrary these days. It's an unnecessary waste of money getting an electric pump or heater for a pond, IMO.