There is 8 billion people in the world, with the number increasing still. You will always have to choose whom you feel responsibility towards, because all 8 billion are beyond anyone's capability.
I feel like you're applying programmer brain to statements that aren't actually commitments but north stars pointing us in the direction of how we should try and do better. Or phrased differently, "We might be the greatest country on earth, but an even greater country would ___"
And in this case to me the blank is "take on the world's tired huddled masses and set them up to be just as self-sufficient and successful as their native born." And I think that's pretty actionable, just about anyone could probably think of more than a few things that would push us closer to this.