I have Thermos brand Foogo 10 oz food cup wide mouth food cup. It works great. I was initially disappointed with it because if you close it tightly enough to keep liquids (soup, hot water) from leaking, then it is challenging for even an adult to open, let alone a young child. So for a long time, I only used it to store hot water for work. It keeps the water piping hot for at least 5 hours. But now I am happy with them for my child's school. I still don't send soups like liquid. But I do send hot solids: pasta, rice, mashed potatoes, etc. I close it, but not super tight. It doesn't leak, and my then 5 y.o. (now 6 y.o.) Kindergartener was able to open it by herself. In fact, she preferred her lunches that way, instead of the usual cold sandwich.
So this is what we've got, although you can probably find it at a local store like Target. I assume that the thermos brand that you found will work just as good as the Foogo to keep food hot.Our Thermos Brand Foogo
We also have KidsKonserve:Stainless Steel Wide-mouth food jar
We ordered that directly from the company. The Company swore that a 4year old would have no trouble opening it, but mine did because I thought you had to close it very tightly. Once started closing it more loosely (as I described above), my dd had no trouble opening it. These were just as good as the Foogo.
We have Fuel, but I didn't use them for hot. I used them for cold. I don't remember very clearly, but I don't think they were nearly as good as the other two that I mentioned above.
So, for you, I think either Thermos brand or Thermos funtainer will be fine. You can keep it hot even longer if you put hot water in the container before putting your hot food inside. I'm too lazy to heat up the water to do so. Thermos is a very good brand.