Bruce sits next to 3 phonetic neighbors — Bryce, Brice, and Drew are the closest matches by sound. Most share Bruce's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"from the brushwood thicket"
"bowman, archer"
"kingly, of royal blood"
"shelter, dwelling"
"from Lucania"
"rule, sovereignty"
"thunder and lightning"
"seven; divine completion"
"defender of men"
"ardor, enthusiasm, fierceness"
"peace power"
"man of peace"
"requested of God"
"one who is learned"
"master of inspired frenzy"
"drawn out of water"
"may God protect"
"he who descends, descent"
"south Munster (place name)"
"keeper of horses, horse servant"
"herb farm, meadow settlement"
Similar sound: These names share phonetic patterns with Bruce — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Norman French origins, giving them the same cultural heritage as Bruce.
Rhythm: Bruce is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.