Insulated containers?

I would use a thermos for soup if you want to keep it hot. There are some with a spoon folded into the lid so you don't have to worry about remembering one.
We also have a small, probable 8oz metal, insulated food container from kleen kantene that my sinuses in his lunch box.

I have packed lunches at various stages of my daughter's life. Different needs over 16 years. These aren't insulated but I really like Pyrex bowls & if you can rewarm in a microwave, they are great. They come in 3 sizes. They are round & come with lids. No issues with plastic. I have also used the lunch blox. They are good for keeping things cold. I have never had much luck with any product which is supposed to keep things hot for more than a couple hours. At 1 time I used Correlle plates which were divided, wrapped them in plastic wrap & were good for rewarming in a microwave. They just had to be kept level. I also had a bento box. It it wasn't suitable for the microwave. Good luck.

Rubbermaid makes a line called (unfortunately) Lunch Blox, modular sets which include cooler units. Can be used for sandwiches, salads, entrees etc. Some lunch bags too. I have not used these, but they look clever and have some good reviews.

For the rectangular or square insulated containers, do a web search for "insulated bento box" or simply type insulated food containers. I think Thermos makes these, might be other manufacturers. Problem you might encounter is the container is not microwaveable.