I've been turned away more often than not by restaurants (of a variety of brands) for attempting to walk/bicycle through the drive-through. I have no idea if it's corporate policy, franchise policy, or incapable exception handling by staff, but the de facto result is that no, you can't reliably go through a drive-through without a motor vehicle (I assume they allow motorcycles, despite that I can't see at all what the functional difference between a motorcycle and a bicycle is from the perspective of a restaurant drive-through).