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"
"bare hill"
"feminized form of Burl with melodic -line suffix"
"noble one, of aristocratic birth"
"born in spring (from Latin verna variant)"
"tuft, bump, rounded protrusion"
"night"
"noble strength (via Audrey root)"
"Island (from the Scottish island of Tiree)"
"blessed, son (Hebrew root)"
"joy, bliss"
"Ruler with a spear; from Germanic ger (spear) and wald (rule)"
"God will increase; from a wooded valley"
"little warrior, dedicated to Mars"
"priceless, praiseworthy"
"spear"
"dear friend"
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.