Yes, lemon meringue pie and upside-down cake can be served together! There are no strict rules against serving different desserts together, and many people enjoy combining different flavors and textures in their meals.
Combining these two desserts could create an interesting and complementary flavor experience. The tangy and zesty taste of the lemon meringue pie can contrast nicely with the sweet and caramelized flavors of the upside-down cake.
If you plan to serve them together, consider the preferences and dietary restrictions of your guests. Some people may have allergies or dietary restrictions that need to be taken into account. It's always a good idea to inform your guests about the desserts being served to ensure everyone can enjoy the meal.
Additionally, if you are serving a larger group, you might want to offer other dessert options to cater to different tastes. Ultimately, it's up to you to decide how to serve your desserts, so feel free to get creative and have fun with your dessert choices!