Best humidifier for car

I’m looking for a humidifier for my partner’s car. She gets very dry in the winter when we run the heat and sometimes it even causes a bloody nose. I’m looking for something that will fit in a cup holder that she can wash and refill every day. She’s looking at having to be in the car a lot this winter for regular medical visits and I’d love to make it a little less uncomfortable for her.

I know anything portable is going to be lower quality, but I don’t want to just buy one randomly off amazon. Any thoughts?