Fire resistant clothing is already available. Hikers who build fires judiciously will use non-sparking wood, which I believe means avoiding most coniferous fuels. Fire retardant sprays for fabric are available: https://www.amazon.com/fire-retardant-spray/s?k=fire+retardant+spray
A better way to stay warm is to carry adequate insulation and eat sufficiently so as to maintain your metabolism. A good many folks who depend upon wood for cooking use packable stoves, which diminish sparks and embers considerably.
Very honestly, i don't think this is much of a problem. i can't recall the last time I caught an ember, but it left a tiny scar, which vanished on the next laundering. When i light a wood fire these days, it is some sort of emergency, and I am not at all concerned with incidental dings to my clothing.
one or more gifts or other benefits from the co-op.