There are various ingredients around the main Centauria region and anyone is welcome to harvest those ingredients. It’s good practice, especially when you first start using the Empires system to see how all the bits and pieces work.
Once you know how everything works there isn’t a massive point in continually collecting and harvesting ingredients unless you have a use for them. Others are unlikely to be wanting to purchase ingredients from you when they can go harvest them themselves.
As the roleplay develops in the AOC there will be opportunities to use ingredients and then it will be much more useful to have various ingredients in your pouch.