You didn't ask me but as someone who also is not a fan, I'll answer. People who love German food probably will love Biergarten. Looooottttttssssss of sausages, pork dishes, ham, pork-based cold cuts, etc plus one or two chicken and fish dishes. There might have also been a beef dish. Then there is a selection of salads like cabbage, potato salad, etc and a bunch of desserts. As a non-pig eater, I struggled. I had a bit of chicken and a bit of fish and then filled up on carbs (pretzel rolls!) and cucumber salad. The desserts were average at best. For me it's simply not a good value. On the other hand, my parents and brother all love pig-based meats so they have a blast here. And the kids found plenty to eat that they liked, plus they loved the show.
So I think the kids would be fine, the egg allergy person would most likely be fine, and the vegan will probably be limited to a handful of the salads and one or two desserts. Only you can know if they would like it. Here is the menu in case you haven't seen it.
Oktoberfest Buffet - Cold Items:
Potato Salad, Cucumber Salad, Tomato Salad, Cabbage Salad, Bean Salad, Sausage Salad, Cold Cuts, Pasta Salad, Liver Sausage, House-made Pickles, Mixed Greens, Rolls and Pretzel Rolls
Entrées:
Soup of the Day, Bratwurst, Regens Burger with Sauerkraut, Oven-roasted Potatoes, Pork Schnitzel, Beef Rouladen, Roasted Chicken, Baked fresh Cod with Mustard and Butter Sauce, Cheese Platter, Red Cabbage, Macaroni & Cheese, Sauerbraten, Meatballs, German Meat Loaf, Spätzle, Roast Pork Ham
Desserts:
Cheesecake, Chocolate Roll, Rote Grutze with Vanilla Suace, Black Forest Cake, Watermelon, Peach-Almond Cake, Apple Strudel, Chocolate Cookies