I really like both of your top choices and if it were me, I’d be tempted to do either [name]August[/name] [name]Dashiell[/name] or [name]Dashiell[/name] [name]August[/name].
Would [name]Stellan[/name] be appealing? (I keep going back and forth on whether this suggestion is too similar for brothers, but strong adoration was my initial reaction)