Fnu sits next to 3 phonetic neighbors — Nu, Nhu, and Fu are the closest matches by sound. Most share Fnu's American English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"first name unknown (administrative placeholder)"
"meadow or clearing"
"overflowing plenty, great fullness"
"capacity to do work (physics)"
"ash tree meadow (from Ashley root)"
"the number six"
"from the boar meadow"
Similar sound: These names share phonetic patterns with Fnu — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have American English origins, giving them the same cultural heritage as Fnu.
Rhythm: Fnu is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.