There might be speculation that the Celts descended from the Berbers, but it seems Ancient Egypt is the more likely of the two.
In the 1440s, a Scottish researcher by the name of Walter Bower wanted to trace the origins of the Scottish people. He thus created a volume of Scottish history called the Scotichronicon. One of his most famous claims was the the Scots descended from the ancient Egyptians, specifically through the daughter of a pharaoh named Scota.
A Greek king named Gaythelos also known as Gaodhal Glas (Gael is said to be derived from his name) was from the region of Scythia. One of his grandsons Niul (a Babylonian) was invited to Egypt as an instructor of languages by a pharaoh and married one of his daughters, Scota. Niul and Scota had a son named Goidel Glas, the ancestor of the Gaels, who created the Gaelic language by combining Babylonian and features of the other languages. During the rule of Miled/Milesius (whose wife was also named Scota) heard about Ireland, and believed it was the island foretold by Moses. Scota and her children eventually reached Scotland where they settled.
Many actually believe that Scota was actually Ankhesenamun, the widow of Tutankhamen. Gaythelos/Gaodhal Glas has also been argued to be Ay, the successor of Tutankhamen. Ay’s reign was cut short and the pharaoh and his wife were forced into exile. It was believed they had travelled to Spain before settling in Ireland.
Whether or not you believe in this “story,” it’s pretty hard to argue against the fact the traces of Egypt can be found in both Scotland and Ireland. Whether it’s the bagpipes, which are traditionally an Arabic instrument, to the jet black hair of many Anglo Saxons, to Gaelic- which has many similarities to Ancient Egyptian. If there’s one thing for sure, we’ve only just scratched the surface.