Gustav sits next to 3 phonetic neighbors — Gustave, Gus, and Augustus are the closest matches by sound. Most share Gustav's German-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"staff of the Goths, divine staff"
"island of the river"
"lone warrior, one fighter"
"people's king"
"son of him who abounds in furrows"
"gift of Yahweh"
"one who runs (occupational surname)"
"victory of the people"
"power of the homeland"
"neighbor, dweller"
"God has remembered"
"short form of Walter"
"glory wolf"
"flowering, blooming"
"firebrand, burning sword"
"who is like God?"
"bold people, brave among the people"
Similar sound: These names share phonetic patterns with Gustav — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old Norse origins, giving them the same cultural heritage as Gustav.
Rhythm: Gustav is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.