Dylan sits next to 4 phonetic neighbors — Dillon, Declan, and Desmond are the closest matches by sound. Most share Dylan's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of the sea"
"bear-king, bear-man"
"God is gracious (via Jack, from John)"
"loyal as a dog"
"Yahweh has shown favor"
"may God strengthen"
"rich protector"
"holder of the heel"
"coal town, dark settlement"
"descendant of Aodh (fire)"
"son of the hood/hooded man"
"short form of Jason, the healer"
"ascended, high"
"home ruler, estate ruler"
"of uncertain origin, possibly barberry hill"
"born on Sunday"
"little fire (via Aidan variant)"
"he who carries the heavens"
"divine messenger, heavenly being"
"noble, mighty of God"
"strong, mighty"
Similar sound: These names share phonetic patterns with Dylan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh mythology origins, giving them the same cultural heritage as Dylan.
Rhythm: Dylan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.