Syon sits next to 4 phonetic neighbors — Zion, Siyon, and Leon are the closest matches by sound. Most share Syon's Hebrew-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"the Promised Land, holy city"
"hay valley"
"he who holds firm the good"
"great, rocky hill"
"modern coinage from la- prefix and -trell"
"sea, ocean (via Kai)"
"truth"
"of Rome, strength"
"ruler of the people"
"one of the primordial ruling gods"
"victory of the people (as short form of Nicholas)"
"of Mars, warlike"
"high and mighty, chief"
"warlike, fighter (from Thracius)"
"combination of Kai (sea/earth) and -ler suffix (one who)"
"God is gracious"
"prince, noble one"
"modern invented name combining Zay and lyn"
"bearer of Christ"
"oak tree"
"power of the people"
Similar sound: These names share phonetic patterns with Syon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew origins, giving them the same cultural heritage as Syon.
Rhythm: Syon is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.