As for who might bake the coronation cake, it's difficult to predict as it would depend on various factors, including the preferences of Prince Harry and Meghan Markle, the reigning monarch at that time, and other members of the royal family. Traditionally, the responsibility for baking the royal wedding cake or coronation cake has been given to a renowned British baker or pastry chef, but exact details would likely be announced closer to the event, if and when it happens.
For the most current and accurate information about such a specific royal event, it's best to refer to reliable news sources or official announcements from the British royal family.