Which tautology is meant by “whole whole”? The 2 words are synonymous, so putting them together adds nothing to the meaning of the word.

If you have only one gadget, then just buy one. Nevertheless if you hear the phrase spoken by someone else, I wouldn’t go as far as to label it incorrect. Grammarly, it’s fine to list multiple adjectives in a row with any modifiers in the vocabulary. Why? What are some examples? Does this sentence add any further meaning?