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"
"God adds"
"gift of God"
"broom-covered hill, beacon hill"
"gray fort or enclosure"
"anointed one"
"God is gracious"
"faith"
"God is my oath"
"eagle"
"of Thor, thunder"
"gentle smile, radiance"
"Variant of Sherman; from the shearing settlement"
"follower of Dionysus"
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.