I'd agree that for a pure UI app that wants to look native, Godot is not the choice (although it's definitely possible to get it close, and theming can help there). For a hybrid however, it can be quite useful. But yes for mobile platforms, lack of touch options is very limiting. Maybe you could expand on when exactly it will be more taxing than a regular app, and also on your third point. I have a simple app that starts up very quickly and doesn't seem to drain battery excessively.