The Sardinian language is so different from Italian that it is considered a separate Romance language, not a dialect of Italian.
I may want to learn that some day, just in case I live among them.
It is also the closest of all the Romance languages to vulgar Latin.
I lived two years in Italy, and my Italian language teacher was from Sardinia, and taught me some words.
Of course, that was 30 years ago and I’ve forgotten far too much of it. Especially since no one speaks Italian in Alabama.
My family’s village in Abruzzo has been on the tax rolls for over 1,000 years. The ruins of the original village, just down the hill, has been dated to 500 A.D. The old dialect there, still spoken by many, is a collection of Italian, Latin, and words that apparently were generated locally and don’t exist anywhere else. A friend from the village wrote a book about it, very interesting.