Ravioli to start - you can buy good ones, or make them and bring them.
I would suggest a savory squash pie but there's no oven, but you can put squash into the ravioli and that is very festive, very christmas.
Another, easier alternative is to make what are known as ignudi, meaning nude ravioli - you take ricotta, lots of grated parmigiano, an egg, and some blanched and well-squeezed spinach (with the limited equipment you have you might want to buy frozen chopped spinach. Salt, pepper and a scrape of nutmeg. If you let the ricotta drain a bit first too, and make sure the spinach is very well squeezed, you probably don';t need flour in it, but a tbsp or two is ok if it seems watery or doesn;t hold its shape. Then form elongated balls, maybe 2 inches long and an inch wide, and roll in flour. You can sit them to dry out a little for a while. Bring water to boil in a frying pan, and then lower to simmering and cook till they float, then drain, add butter and parmigiano. Or sage butter.
Another easy alternative is squash gnocchi - steam or microwave squash and put to drain. The best are the low dark green bumpy kinds that are sort of pumpkin shaped, but any flavorful and creamy type is good, acorn, butternut. Cool somewhat, then add egg, salt and pepper and enough flour that it holds its shape on a spoon. Drop by spoonfuls into simmering water, drain when they float. Season with butter or sage butter, lots of parmigiano.
I find these to be very special dishes and though in Italian culture they are first courses, you could make them the main. But even if you use them as a first course, they give you a really festive feel. And since they're filling they don't require all that much later.
If they're not meat lovers, you don't have to go with chicken, you can certainly do stuff without meat at all. It's common belief that a good meal has to have meat but really, the otehr dishes are way more complex and unusual and can be a wonderful and festive dinner.
Sauced vegetables are nice, like cauliflower or broccoli with an interesting creamy sauce. a really good beet salad - go for contrasting colors, ,like beets with string beans, rocket (arugola, rughetta, whatever you call it locally), pine nuts, maybe some hard boiled eggs, or seived hard boiled yolks on top, a nice vinaigrette. It looks very christmassy. It can be cold or warm.
If you go with the ignudi, you could begin with a pumpkin soup, then the ignudi as a main course with the beet salad as a side, and always, i think, the thing that makes it christmas is to have various complex or unusual sides. Artichokes for instance. I posted a recipe from tuscany that can be made in a sautee pan - if you can't find it i can look for it.
What makes it a christmas dinner is not the meat, but the specialness of the dishes. (And I say this as a real meat lover, by the way). We really should stop thinking of meals as defined by the meat course. It limits our creativity. Piece of meat and a salad is not an interesting meal.