"What more" is a common expression that is used to convey a feeling of surprise or disbelief at something that has been said or implied. To express the same sentiment in other ways, one could use synonyms such as "furthermore," "besides," "additionally," "moreover," or "in addition to." These words all serve to emphasize the point being made, while also conveying a sense of incredulity or wonderment. By using synonyms for "what more," speakers and writers can add depth and nuance to their language, making their expressions more interesting and engaging for their audienes.