Oh, come on, you can use it for everything. I had coffee thermos, but it was pretty big, so I used it for food as well. It was a real hell when I tried to clean it after, but I just found an article at
https://keepithot.co/how-to-clean-a-thermos and learned how to do it properly. If you don't want to spoil yours, you can buy and use another one, but.. trust me, you don't need an extra one, if yours is pretty big. Just try once and then decide if that's suitable for you.