It’s more important that each element communicates the correct role based on its function, even if it’s the only element of that type in the group. A link should only take the user to a new location. A button should perform an action, such as opening a modal or executing a search.
It’s not unusual for users to encounter multiple element types in footers. When elements have correct roles, users on assistive technology can better understand and predict what will happen when they activate each one.
For step-by-step help for identifying and understanding interactive element roles, explore the Guided Manual WCAG Audit Tool from Accessible Web.