My side hustle (which can hopefully be a main hustle in a year or less) is a food manufacturing business. I won't get too detailed since the industry is pretty tight knit and being one of the only Blacks will give me away but I will drop it is a fermented product.
Getting started in food manufacturing can be a firehose type experience. You have to not only learn how to make the product good (duh) but maintain this quality as you scale the production. In addition you have local, state, and federal (FDA) guidelines you have to follow and spot inspections where they ask everything about safety, sanitization, refrigeration, etc.
I started out in a shared kitchen which is a commercial kitchen set up where you can rent time in a place that is already approved by the health department. This was invaluable as I could pay for flex time when my business was young and didn't have to buy all the kitchen stuff (3 bay sink, hand wash sink, chemicals, etc.) A lot of hot sauce guys do this.
The only issue with food production though is depending on the type of food, it is pretty capital intensive. Luckily with fermentation (as opposed to baking, etc.) I was able to build a lot of my own equipment or buy used stuff that saved tens of thousands of dollars. Then once the operation is up you have to sell, sell, sell. Luckily I have some store and distribution accounts as well as Amazon to push product.
I got my own place about a year ago and the rent is a killer but I am finally making it over the hump and I think I will soon be able to pay down a good portion of the debt and hit prime time knock on wood.