Joni sits next to 4 phonetic neighbors — Jonah, Joni, and Johnny are the closest matches by sound. Most share Joni's Scandinavian cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"God is gracious"
"invented name, no inherent meaning"
"of the sea, the pool"
"stony ford"
"hospitality toward strangers"
"one who does not speak, baby"
"settlement of Ella's people"
"nobleman, patrician (via Patrick)"
"God is gracious"
"gift of God (via Zane/Zayn root)"
"maker of cauldrons and cookware"
"son of Rath (prosperity)"
"God gave"
"prince, commander"
"at the mountain"
"treasurer, keeper of treasure"
"continuous improvement"
"slender, graceful"
"carrier of burdens"
"belonging to Artemis"
Similar sound: These names share phonetic patterns with Joni — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew via Scandinavian origins, giving them the same cultural heritage as Joni.
Rhythm: Joni is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.