Sung sits next to 5 phonetic neighbors — Song, Sun, and Soong are the closest matches by sound. Most share Sung's Chinese cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"to succeed, accomplished"
"bright fame"
"exalted, high mountain"
"of Thor, thunder"
"God is my oath"
"prince, hill settlement"
"gift of God"
"wise counsel, gentle (ewe)"
"God is gracious"
"gray fort or enclosure"
"valley; place"
"honoring God, one who honors God"
"God adds"
"anointed one"
"Variant of Sherman; from the shearing settlement"
Similar sound: These names share phonetic patterns with Sung — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Korean/Chinese 成 origins, giving them the same cultural heritage as Sung.
Rhythm: Sung is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.