Sonnie sits next to 4 phonetic neighbors — Sunny, Sonny, and Donnie are the closest matches by sound. Most share Sonnie's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"sunny, bright, cheerful"
"old friend, wise friend"
"the sun, solar light"
"traveler, crossroads"
"Yahweh is God"
"settlement among the undergrowth, brushwood farm"
"oak tree by the pool or stream"
"deep valley dweller"
"ridge settlement"
"related to Samir: lively conversationalist"
"dark, dusky"
"from Hadria (a Roman city)"
"Short form of Uilliam, the Irish form of William"
"from the high place"
"alive, full of life"
"noble, superior"
"emperor, ruler"
"will-bright, famous will"
"God is gracious"
"victory of the people (via Nico)"
"spear ruler"
Similar sound: These names share phonetic patterns with Sonnie — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have English origins, giving them the same cultural heritage as Sonnie.
Rhythm: Sonnie is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.