While homemade gunpowder can be useful, it is usually made by homesteaders or historical weapons enthusiasts. Or people who want to learn primitive and ancient skills.
Gunpowder was invented long before cannons and muskets. It is one of the Four Great Inventions from ancient China, the other three being a compass, printing, and paperwork. The history of gunpowder begins in the 2nd century AD. Taoist alchemists experimented with sulfur, saltpeter, and other powders to create an elixir of immortality! While we can’t prove that they created gunpowder, one of them wrote about “the mixture of three powders that fly and dance violently”.
Ancient Chinese civilization is so fascinating with its blend of philosophy, magic, and science. Even a compass had been used for fortune-telling and geomancy for hundreds of years before it has become a navigating tool! Anyway, back to our story, for the next 7 hundred years there are occasional references to gunpowder-like mixtures and formulas. They were still a part of the quest for eternal life. We don’t know how it worked and if it was useful.