You’ve repeated this a few times, but I clicked on several charcoal options on Home Depot’s website, and they claimed to be made entirely of “100% natural hardwood”. Maybe some cheaper ones have added coal?
Take Kingsford, for example, probably the single most popular brand of briquettes at Home Depot. It does not say 100% natural hardwood, it says 100% natural ingredients, including wood. Coal is natural. And 15-40% of Kingsford briquettes [0].
[0] https://www.thecloroxcompany.com/wp-content/uploads/kingsfor...