Dillon sits next to 4 phonetic neighbors — Dylan, Dilan, and Dillan are the closest matches by sound. Most share Dillon's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"great sea, son of the sea"
"joy, happiness, gladness"
"dawn, bright star"
"bright, splendid (folk etymology)"
"sparkling, clear"
"grace, favor"
"bent river"
"calm waters, peaceful"
"feminine diminutive of Charles"
"pleasant wood (via Marley)"
"golden lily (modern blend)"
"small bunch of flowers"
"the precious metal, lustrous and bright"
"modern invention combining energy and grace"
"pearl"
"blue jay bird (from Jay)"
"early night, swift shadow"
"daughter of the sea"
"one who works with tannin"
"honesty, veracity, reality, that which is real"
"she who looks out"
Similar sound: These names share phonetic patterns with Dillon — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh 'dy' + 'llanw' origins, giving them the same cultural heritage as Dillon.
Rhythm: Dillon is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.