Oona sits next to 3 phonetic neighbors — Una, Luna, and Nona are the closest matches by sound. Most share Oona's Irish-rooted cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"lamb"
"rocky hill, tower"
"full of grace, star of the sea"
"my God is abundance, consecrated to God"
"goddess of wisdom and crafts"
"healer, physician"
"ancient capital city"
"woman from Magdala"
"of the wild, forest creature"
"bright, shining light"
"of the clan of Bricius"
"warlike, brave"
"charcoal farm"
"grace and devotion to God (Anna + Elisa)"
"bright, clear, famous"
"island of Kell, Kell's island"
"clear, bright"
"good, goodness"
"free person (feminine of Charles/Karl)"
"exalted, high, strength"
Similar sound: These names share phonetic patterns with Oona — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old Irish origins, giving them the same cultural heritage as Oona.
Rhythm: Oona is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.