I have lit up an LED using the cold heat iron. I’d be afraid to fry circuits and chips with that. Another thing is the darn tips. They are fragile and cost more than a good standard soldering iron. Stick with old school irons.
I have one of these and it works pretty well, at least for quick patch jobs (broken solder on a button for example). Its 15 watt, pencil tip, and heats/cools quickly. I just don’t know how long the batteries last on it.