NOTHING!
You do not need to buy anything The bottom line is you have to use the tool to get healthy. A small Plate can not do it if you put COOKIES in it, I did not buy a single special thing and used what I have in house already.
Now what you need to buy is healthy food, have a good plan, and master the art of Smoothies and Shakes. The key to this is you change in lifestyle not your change in plates and accessories.
Ok that was harsh but a fact
Now if you think buying all these gadgets will make you happy and successful for sure buy them, As for Meal prep You can get containers on Amazon if you do that kind of prep. I personally do not prep for myself but do prep for my kids who are on a insane work out and healthy fitness goal. I love to prep a meal - Chicken Asparagus and fruit and vacuum seal them for them. They just drop them in the Souse Verde open and done! So that may be a way for you to prep for days.
For now Set the plan and goals then as you progress down the path get the system that works best for you. You will love this journey and welcome