Nation sits next to 3 phonetic neighbors — Mason, Nathan, and Nason are the closest matches by sound. Most share Nation's Latin-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"a people, a community"
"oak tree"
"ridge settlement"
"spiral, coil"
"possibly from Vashti, beautiful"
"tower"
"from the stone settlement"
"the king (colloquial interpretation)"
"tools of the wizard, instruments of healing"
"son of Ryer, from the rye field settlement"
"oak tree by the pool or stream"
"emperor, ruler"
"the writer, the recorder"
"manly warrior ruler"
"light"
"rejoicing, celebration"
"one who follows"
"the wind"
"God is gracious (via Sean)"
"river, river that swallows rivers"
"pilgrim, traveler, foreigner"
Similar sound: These names share phonetic patterns with Nation — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Nation.
Rhythm: Nation is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.