thank you for sharing your question with the wefugee community!
If you are thinking of starting your own business with a food truck, then many documents and applications have to be dealt with or procured before the first burger / salad etc. is sold. There is still a long way to go before the opening.
First of all you have to clarify whether you can start your own business in Germany with your residence status (do you come from the EU or from another country). Your first challenge may arise at this point. To get a first idea and first information about it, the following page of the nationwide funded IQ network (integration through qualification) will certainly help you (https://www.wir-gruenden-in-deutschland.de/informationen/) For a better understanding , you can set your language!
For further details, which also include your very personal situation, I would also recommend that you contact the IHK in your area. The IHK Region Stuttgart has compiled a good overview of self-employment/food truck that can be viewed online (https://www.stuttgart.ihk24.de/branchen/tourismus/aktuelles/gruendung-eines-foodtrucks-3587326)
Also the question of your german skills need to be asked, since the process to a self-deployed business without sufficient german skills seems to be a very big hurdle.
Since the path to self-employment is very complicated and requires many different points, there are special preparatory courses to help you get an overview of self-employment. Certainly there are such courses in your region. I would also be happy if you would contact me again with further questions. I'm a consultant with mbeon and I‘ll be glad to help you over a longer period of time. Mbeon is an online advice for migrants via the mbeon app, which you can install on your smartphone for free. Download it from App Store or Google Play Store. You can find me in the mbeon app and get confidential individual advice in a secure virtual space without other people reading our conversation. Further information: www.mbeon.de.
All the best,