You can certainly as ask if there is some special food you can eat that doesn’t interfere with your special diet. Or you can see if there is some non-food way to “celebrate”.
But there is no particular expectation that you must do anything special for the last day before Lent begins. While some people do use the day to eat special foods, for many people it’s just another day. There are others who take it as an opportunity to use up food items that they don’t want around to temp themselves once Lent begins.
