Tierra claim their new jacket is the first in the world comprised entirely of 100 percent plant-based materials...
What about Cotten?
They’re probably referring to mass-produced cold-weather outerwear, which usually does have synthetic components now.
I have a Caterpillar jacket that’s entirely synthetic; the warmest parka-type thing I’ve ever owned.
Elk hide is plant based
Henry Ford took a stab at soy-plant and hemp fibers for clothing. Got sidelined by cheap oil-based fabrics that wore better, before he could fix the shortcomings.