Nels sits next to 5 phonetic neighbors — Neil, Niels, and Nels are the closest matches by sound. Most share Nels's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"champion, cloud"
"black banded gemstone"
"descendant of Raghallach"
"little warrior"
"son of Rath (prosperity)"
"my God is strength"
"battle camp"
"one who owns date palms"
"hollow, vain (from Latin Cassius)"
"sea-connected, modern creative"
"thunder stone"
"street"
"continuous improvement"
"the best, most excellent"
"belonging to God"
"little warrior or little church man"
"supplanter, one who takes another's place"
"diminutive of Nicholas"
"servant of God"
"Dane's settlement"
"modern coined name, possibly hillside light"
Similar sound: These names share phonetic patterns with Nels — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Irish Gaelic via Scandinavian origins, giving them the same cultural heritage as Nels.
Rhythm: Nels is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.