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Peel contains about 40-50% dietary fiber and has been considered as a new source of dietary fiber in bread making. In addition to these, peels are rich source of phenolics and fair source of vitamins like riboflavin, ascorbic acid, folic acid and vitamins B6.

https://www.researchgate.net/publication/287292063_Composition_and_health_benefits_of_potato_peel#:~:text=Peel%20contains%20about%2040%2D50,folic%20acid%20and%20vitamins%20B6.

While the potato skins offer about half the nutrition of the potato meat – they still have plenty to offer including fiber, iron, and vitamins C and B-6. The skin does outrank the potato meat in some important categories. For example, for a whole baked potato, the skin has 115 calories, 27 grams of total carbohydrates, three grams of protein, which is equal for both meat and skin, and five grams of fiber. Meat only has two grams. The skin of a whole baked potato provides 88-percent of the total amount of iron. Along with iron, the meat and skin of a potato provide an abundance of key minerals that lend to the overall health of muscle contraction and nerve transmission.

https://agnetwest.com/nutritional-value-potato-skins/