If you are invited to a dinner party, it is often a good idea to bring something along. The question is what might be welcomed, and what might be embarrassing. You can ask, but too often the host or hostess will suggest you bring nothing. That is just a polite response, and that response may not be something you should follow.
You do have several options, but one is certainly not the main course. The main course is the part of the meal that sets the tone for the event, and that should be left to the host or hostess. It is always inappropriate to bring a second main course, especially if it upstages the one chosen by the host or hostess.
Sparkling water comes in many flavors, and I would wonder which to choose.
blackspanielgallery, Thank you for pictures, practicalities and products.
In particular, I appreciate your gentle reminder about not upstaging anyone or anything and your thoughtful suggestion about leaving decorative boards with the host/hostess.
This past year, I discovered sparkling water brands carried by the local manifestations of a nationwide grocery-store chain. What do you think of bringing that by itself (questionable since each bottle cost 59 cents last year, 69 cents this year) or, for instance, with cutting-board food, side-dishes or desserts?