Please ask everyone, when I see someone's travel notes mentioning that in January, overnight parking in Norway requires electricity to protect the car and start the next day. What kind of device is this? Will the car rental company provide it? If not, will the car not start the next day if parked outdoors ?

That's a misunderstanding. Some car dealerships will provide a power cord that you can plug into a power outlet next to your parking space. The main purpose is to warm up the car a bit before getting in, so you're not too cold when you sit down. It's definitely not because of starting the vehicle. I drove by myself in Norway from late January to early February this year, and I didn't have this power cord. I started the car normally every day, but my butt was a little sore.