Nyelle is likely a modern variant influenced by French-style endings and names such as Noelle or Nielle.
Nyelle is a contemporary feminine name built on an ancient Irish and Scottish foundation. Its closest ancestral form is Niall, a Gaelic name of uncertain but rich etymology — leading theories trace it to niadh (champion) or to a proto-Celtic root meaning "cloud" or "passionate." Niall became Neil in English, then Nell as a feminine diminutive, and the lineage continued through Nella, Nielle, and eventually the more inventive modern forms that add a distinctive Y and final E to signal freshness.
Niall of the Nine Hostages, the semi-legendary High King of Ireland who may have lived in the late fourth or early fifth century, gave the name its most mythologized bearer — a warrior-king whose descendants (the Uí Néill dynasty) dominated Irish politics for six centuries and whose Y-chromosome is said to survive in a remarkable percentage of men with Irish ancestry today. That ancient lineage gives even a modern form like Nyelle an unexpectedly deep root system. The spelling Nyelle also evokes niello, the beautiful black metalwork inlay technique used by medieval craftsmen on silver and gold, adding an unexpected visual art reference to the name's resonance.
In contemporary use, Nyelle appears primarily in the United States, where its combination of familiar sounds (the NY- cluster common in Nyah, Nyla, Nyomi) and elegant length gives it wide appeal. It is rare enough to feel individual, familiar enough to feel natural.