Something to appreciate with thoughts like this are the more natural dyes that come from plants, such as Iris Root, Black Walnut, Reed Flower, Hawthorn, so forth.
I've seen folks online use Virginia creeper and pokeberry to dye fabrics, a soft green and vibrant purple respectively. I'd love to take a crack at them on cotton, maybe even a natural tie dye!
I've read that in the southeastern states, Spanish moss was used like wool, also for thread and upholstery. But it doesn't get nearly as cold down there 😆
You put it best there, I live in a part of the United States that gets over 100 degrees during the summer time, which would challenge a cloak idea sadly