Johan sits next to 4 phonetic neighbors — Joanna, Johanna, and Joan are the closest matches by sound. Most share Johan's Dutch-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"God is gracious"
"spear ruler"
"bad settlement"
"lilac, bluish"
"elaboration of Audrey with French -ene suffix"
"variant of diminutive feminine names"
"little warrior, dedicated to Mars"
"the dawn, daybreak"
"noble one, of aristocratic birth"
"Island (from the Scottish island of Tiree)"
"rounded growth on tree, knotty wood"
"little Jon, feminine form of Jon"
"dear friend"
"God will increase; from a wooded valley"
"shining bright, torch (from Elaine/Helen)"
"Ruler with a spear; from Germanic ger (spear) and wald (rule)"
"feminized form of Burl with melodic -line suffix"
"blessed, son (Hebrew root)"
Similar sound: These names share phonetic patterns with Johan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Hebrew Yohanan origins, giving them the same cultural heritage as Johan.
Rhythm: Johan is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.