I have two citrus trees that are in large pots. I just cover them and put a 100w light bulb under the blankets when the temps get close to freezing. I like to keep the tomato plants outside so they can ripen naturally.
What ever works. I have thought about using a small hoop green house with a 100 watt bulb outdoors in the winter too.
What keeps me from it, is my aversion to cold weather. I wouldn’t want to even go outside long enough to turn the light on or off.
It’s great that we have various options to grow our own stuff, I think.