In our house, my child has the same lunch every day of the week so I am not much help with suggestions for winter lunch ideas. Perhaps sausage rolls or scrolls or some warm pasta if you have a container that could keep it warm throughout the day and doesn’t require reheating.

No, not really much difference in our household. My kids were and are never keen to bring a thermos with them (even though I have them at home and ready for use).
Mine often would bring a full lunchbox home and then would start heating things up and eating after school.

We use our thermos a lot for migoreng noodles, pasta, or whatever leftovers from the night before, seasonal fruit and veg, or something like homemade onigiri. Unfortunately my kiddo is anti-sandwich or I would 100% be sending sandwiches a lot more often!

Like the others have already said a thermos is a very good option. My daughter loves to have sausage rolls or stirfry noodles without the meat, which are both very easy to make at home. The awesome thing is that they come in different sizes. I have also packed a toasty into an insulated lunch bag. It worked to keep the toasty warm but unfortunately it does go a bit soggy due to condensation but the bag is a good option also in keeping things warm.

Like the others said, a thermos is great! My daughter loves having stir fry noodles with no meat, also sausage rolls which are super easy to make at home! You can get them in multiple sizes too or even just an insulated lunch bag for something they could eat during their first break? I’ve done that before with toasties. It kept them warm but they didn’t stay crispy and went a lil bit soggy due to the condensation but the bag itself could be a good option.

Thermos with fried rice, usually just with egg, peas, corn, some soy sauce and sesame oil. Because it’s in the thermos, I don’t secure the lid tight tigh, as with the heat it’s hard to open later on, and with rice even if accidents happen, it would be a pain to clean

I loved having a thermos of warm soup to take to school when I was in upper primary and high school. Other than that there isn’t too much that can really stay warm. I’ve seen some lunch boxes that have hot water poured into a section to keep it warm but I’m a bit iffy on that